AC Controllers/Amplifiers
AC Controllers/Amplifiers
AC Controllers/Amplifiers
AC Controllers/Amplifiers
AC Controllers/Amplifiers
AC Controllers/Amplifiers
AC Controllers/Amplifiers
AC Controllers/Amplifiers
AC Controllers/Amplifiers
AC Controllers/Amplifiers
AC Controllers/Amplifiers

AC Controllers/Amplifiers

Messerworks LLC
$219.99 $189.00 Save $30.99

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AC Controllers/Amplifiers 

 

Offered by MR2 Heaven in collaboration with Messerworks LLC

All units are built and tested prior to shipping

 

Replaces the beige or black AC amplifier under your dash that is discontinued and no longer available from Toyota.


Which unit does your car need?

Toyota fitted three different A/C amplifiers across the SW20 run. They look alike, they are not interchangeable, and between them the terminal numbering changed completely. Five minutes with a torch settles it — and it is the one thing you must get right before you order anything on this page.

  1. 1

    Find the amplifier and read its label.

    It is the box the A9 harness plug goes into, behind the center console under the dash. On the label is a Toyota part number beginning 88650-. That number is the answer — not the year, not the engine.

  2. 2

    No label, or unreadable? Count the wires.

    Count the populated cavities in the A9 plug. 14 populated is the -17120 family. 16 is the -17130 family. The two extra wires on the later car are a brown BR — the amplifier's own output to the engine ECU — and a brown/white BR-W strap.

  3. 3

    Use the build date as a cross-check, never as proof.

    US 1991 is almost always -17120. US 1993–95 is -17130. A US 1992 car has to be read off the label — the changeover happened in December 1991, which falls inside that model year. Any car built from December 1991 onward, in any market, is -17130.

  4. 4

    Has the engine been swapped?

    Then you want the Swap Edition — but only if the car started life with a -17120. A swapped car that came with a -17130 should wait for Unit B, whose firmware can switch the extra outputs off.

     

    Swap Edition — make sure this is actually your car

    The Swap Edition is built for one specific situation. Check these four things before you spend anything; if any of them is not you, the lineup has the unit that is.

    • ReplacesAmplifier part number 88650-17120 — the beige unit on early cars. That part number is what the Swap Edition was designed against. A -17130 car needs Unit B.
    • EngineAn engine swap — 2GR-FE or similar. The A/C circuit itself is stock MR2, so what matters isn't which engine, it's that the original engine-management side of the amplifier's job is gone.
    • TransmissionManual. Automatics used an extra amplifier terminal that isn't part of this build — a stock automatic is covered by Unit A.
    • ECU signalYour swap ECU takes its A/C input as +12 V from the same wire that engages the clutch. That's the factory B-W signal path, and it's how this controller hands your ECU the idle-up request. If your ECU expects a ground instead, talk to me before ordering.

    Then confirm the amplifier is really the fault

    This takes ten minutes and tells you whether you need this part or something cheaper.

    1. 1

      Your refrigerant charge is good.

      A low system won't engage the clutch no matter what controls it — the factory pressure switch cuts it off. Check the charge first.

    2. 2

      Grounding the L-O wire engages the clutch.

      At the amplifier plug, jump the blue/orange wire to ground with the engine running. If the compressor kicks in and you get cold air, your compressor, clutch, relay, and refrigerant are all fine — the amplifier is the failure.

    3. 3

      Your A/C button does nothing.

      12 V shows up on the pink wire when you press it, but the clutch never engages. That's the amplifier failing to close the loop.

    If grounding L-O does nothing, stop. Your problem is upstream — relay, fuse, pressure switch, compressor, or charge — and this controller will not fix it. The full diagnostic checklist ships with every order, and if you're not sure what you're seeing, email me before you buy and I'll talk it through with you.


    What it actually does

    The factory amplifier had five jobs. This reproduces all five, from the same wires, at the same plug.

    Clutch control

    A logic-level MOSFET grounds L-O to energize the A15 clutch relay — exactly what the OEM unit did, with no mechanical contacts to burn.

    Freeze protection

    Reads your factory evaporator thermistor and cycles the compressor with proper hysteresis plus minimum on/off timing. No short-cycling, no iced core.

    Engine-run detection

    Senses alternator charging voltage with hysteresis and a dip-grace timer, so the compressor's own engagement sag doesn't drop it out. Key-on with the engine off does nothing, same as stock.

    Radiator fans, both stages

    An on-board relay sources 12 V to the fan enable circuit, and a second output holds the motors in series for LOW — releasing to parallel HIGH above ~90 °C. The factory behavior most replacements skip entirely.

    Pressure safety left in hardware

    Your A13 dual pressure switch still gates the relay's power feed. High or low refrigerant pressure cuts the compressor whatever the software thinks. That circuit is untouched.

    Idle-up signal

    The B-W wire — 12 V only while the clutch relay is closed — is the factory signal path to the ECU's A/C input. Tap it and your ECU raises idle under compressor load.

    Why swapped cars first

    When you swap an engine into an SW20, the A/C amplifier loses half its job. The vacuum idle-up actuator it used to drive is gone with the old engine, and the igniter signal it watched for the high-RPM cutout belongs to an ignition system that isn't in the car anymore.

    A swap ECU handles those itself. It just needs to be told the compressor is engaging — and it wants that as +12 V on the same wire that closes the clutch relay. So the controller's job gets simpler and cleaner, and everything left is A/C circuitry that's still pure MR2.

    • Tape off the vacuum idle-up wire. There's no actuator on the other end of it anymore.
    • Tap B-W to your swap ECU's A/C input. It goes +12 V only while the clutch relay is closed, so your ECU raises idle exactly when the compressor loads the engine.
    • Everything else stays factory. Same plug, same sensors, same relays, same pressure switch.

    This is the configuration it was built and driven on — a 1991 SW20 with a 2GR-FE and a manual gearbox. Not a design on paper waiting for a first customer to find the problems.
    Exploded view of the controller: enclosure lid, populated PCB with relay, MOSFETs and screw terminal, and enclosure base with mounting bosses.

    Board, enclosure, and hardware. The whole assembly is 90 × 70 mm. The housing is printed in ASA — not PLA — so it holds its shape through a closed-up summer behind the dash and won't go brittle in UV.

     

    Designed against the factory manual, not guesswork

    Every terminal on the board was audited against the 1991 electrical wiring diagrams — page by page, wire by wire.

    Copper-verified

    The routed 2-layer PCB was checked net-by-net against the netlist before a single board was ordered.

    Fails safe

    Boots with the clutch off. Loss of signal drops the compressor rather than latching it on. Reverse-polarity Schottky and a TVS sit at the supply input.

    The traps are documented

    Identify the thermistor pair by measuring ~1.1 kΩ, never by pin number. The 12 V feed is R-L off the GAUGE fuse — not L-R, a different wire in the same loom. The W3 switch is a fan switch, not an overheat cutout, and is deliberately unused. These are the mistakes that cost me time; they're written down so they don't cost you any.

    43 wires, each numbered

    The wiring guide is plain English, in order, with a full J1 position map. No schematic literacy required.

    Full wiring schematic of the SW20 A/C controller showing every numbered connection between the factory A9 plug and the board.
    The complete schematic — included with every order, at every tier.

    One screw terminal (12 to 15 positions, by unit). Every wire lands in a labeled position — no connectors to crimp.

    Sealed printed enclosure with ziptie tabs — mounts where the old amplifier lived, or anywhere dry behind the dash.




FAQs: Availability, Orders & Shipping

All in-stock orders placed before 3:00 PM PST generally ship the same business day.

Orders placed after 3:00 PM, on weekends, or on holidays will typically ship on the next business day. While we work hard to get every in-stock order out as quickly as possible, processing times may occasionally vary during high-volume periods.

Please use our shipping calculator to calculate your shipping costs.

Due to our bot protection, you must enter three dots (...) in Address Line 2 to activate the shipping calculator.

Please note that we also offer two preset shipping options of $40 and $60 for orders that require manual shipping quotes. If the actual shipping cost exceeds the selected preset amount, we will invoice you for the remaining balance.

Most small packages cost under $40 to ship. Most small items that fit in an polybag costs around $5 or so for CONUSA shipping.

Our shipping calculator provides estimates and may not always accurately reflect shipping rates for larger items, oversized packages, or complex/multi-item orders. If you are unsure about the shipping cost or need assistance, please feel free to contact us and we’ll be happy to help.

We offer a range of competitive domestic and international shipping options to fit your needs and budget.

Need your order fast? Expedited services, including Next Day Air and other express shipping options, are available at checkout when supported by the destination and package.

Need multiple orders shipped together? We offer package consolidation services when needed and may be able to combine eligible orders into a single shipment, helping simplify delivery and potentially reduce shipping costs.

Contact us before your orders ship, and we'll do our best to accommodate your request.

If an item is In Stock, it is ready to ship and will be packaged and sent out as quickly as possible.

Because many of our products are produced in limited quantities, popular items can sell out between production runs. With production and manufacturing lead times often ranging from 1-3+ months, unexpected demand can quickly deplete available and planned inventory, and waiting for future production runs may mean missing one—or even multiple—batches and facing a significant delay.

Pre-Orders help us accurately gauge demand and plan production quantities while allowing customers to secure their spot & receive their parts in a timely manner. This helps reduce delays and the chances of products selling out unexpectedly, while ensuring we can continue bringing more specialized products to the community.

Not all pre-orders are the same. Depending on the product, a pre-order may be for an existing product that is temporarily sold out or a new product that is still in development.

The product page will provide the most current estimated fulfillment timeline and any relevant project details.

Restock Pre-Orders — Existing Products

Many of our products are produced in limited quantities, and popular items can sell out between production runs.

If an existing product is sold out, we may open a pre-order for the next production batch. These products have already been developed and produced previously, but additional manufacturing time is required before the next batch is ready.

Pre-ordering secures your place in the next production run and ensures you don’t miss the next available batch.

Development Pre-Orders — New Products

Some pre-orders are for completely new products that are still being developed.

Developing a new product is a significant process. Depending on the complexity of the project, it may involve:

  • Product design and engineering
  • Prototyping and testing
  • Tooling and mold development
  • Fitment and quality/mold revisions
  • Manufacturing preparation
  • Final production and quality control

A single product can take 3 months to over a year to fully develop before it is ready for regular production.

During this process, prototypes, molds, fitment, or manufacturing methods may require revisions. If we identify an issue that does not meet our standards, we may need to make corrections before moving forward with production.

This can occasionally extend the estimated timeline, but we believe it is better to correct an issue before shipping rather than rush a product to customers that does not meet our standards.

We always aim to provide the best estimated timeline available at the time a pre-order is listed.

However, estimated dates are not guaranteed. Manufacturing schedules can change, and development projects may require additional time for prototyping, revisions, production, or quality control.

We do not believe in rushing production simply to meet a projected date.

Before a product ships, it must go through the appropriate manufacturing, finishing, fitment, and quality control processes to ensure it meets our standards.

If there are any significant changes to the estimated timeline, we will provide pre-order customers with updates as information becomes available.

Good products take time. We'd rather get it right than get it out fast.

Our goal is to continue supporting the MR2 community by developing new and unique products that may not otherwise exist.

Pre-orders and group buys allow us to better determine demand and commit to larger production quantities. Larger manufacturing orders can help reduce per-unit production costs, allowing us to pass a portion of those savings directly on to our customers while also helping fund the development of future products.

By participating in a pre-order, you are not only securing your product—you are also helping make new projects possible.

Depending on the project, participating in a pre-order or group buy may provide:

  • Up to 20% off or more on future regular product price
  • Priority access before regular inventory becomes available
  • The ability to secure your place in a limited production run
  • The opportunity to help bring new, community-requested products to market

Because pre-orders and group buys allow us to commit to production quantities, tooling, manufacturing, and product development, pre-order purchases are generally non-refundable once the order has been placed.

If you no longer wish to wait for your pre-order, you may have the option to convert the full amount paid into MR2 Heaven store credit, which can be applied toward MR2 Heaven-branded products.

Please note that pre-order fulfillment timelines are estimates and may change due to manufacturing, fitment, quality control, or other unforeseen development delays.

In the unlikely event that a product is ultimately unable to be produced or the project is permanently canceled, all affected pre-order customers will receive a full refund.

Thank you for supporting our projects and helping us continue to develop new products for the MR2 community.

Have a question or need assistance? We're here to help. Send us an email at Sales@MR2Heaven.com or reach out through our Contact Us page, and our team will be happy to assist you.

Customer Reviews

Overall rating: 4.9 / 5 from 1601 reviews.

Customer photo review of Mad PSI Carbon Fiber Ducktail Trunk Lid

Very happy with the look of my new pre-preg carbon duck tail trunk, was exactly what my car was missing. The Mr2 heaven team was very helpful with all my requests during the purchase. Will come back soon for getting more high quality parts! Thanks.

Ricardo M. 5/5 Verified

Mad PSI Carbon Fiber Ducktail Trunk Lid

Customer photo review of MR2Heaven Adjustable Turbo/NA Shifter Cables

After my 2GR swap, my 5th gear was only millimeters from the upper right corner. It was so tight that I couldn't even use a boot. 2nd gear was about where neutral should have been. These adjustable cables fixed the issue having both cables maxed out in length. The left/horizontal cable could have used another quarter inch of travel as going into first there will be some contact with the cable bolts, but shouldn't be too bad. I may just have to grind the bolt down some if it becomes too noticeable. Edit. I found a small spacer in a box of other parts shipped which extends the left cable so these are now perfect. Obviously they've encountered this in the past and have added the spacer. I'm just a little late in the MR2 upgrades as I got 420k out of my (mechanically) original mr2.

Mark W. 5/5

MR2Heaven Adjustable Turbo/NA Shifter Cables

Customer photo review of MR2Heaven East Bear Style 91 Spoiler - Fiberglass and Carbon Fiber Available

Needs some adjustment but if you buy Glassfiber thats somthing to expect, so if you can do boodywork and smoothen the edge down and join them togetter you will have a super clean looking wing that not many have, this is the wing you need if you dont want what everyone has on their Sw20 and it looks amazing with the right work put into it

Oliver M. 4/5

MR2Heaven East Bear Style 91 Spoiler - Fiberglass and Carbon Fiber Available

Customer photo review of MR2Heaven E-Brake Cables (For OEM Brake Calipers)

I have a working ebrake again!!! Straight foward install, had to work some of the metal on the car so the yellow plastic grommets on the cable stay in place. Also one of the pins wasn’t sliding in at all so I grounded it down and then I slightly drilled the yoke on the cable for an easy fit. I would have gave it 5 stars but I did have to do some work to make it fit so it gets 4 stars

John H. 4/5 Verified

MR2Heaven E-Brake Cables (For OEM Brake Calipers)

Customer photo review of MR2Heaven Reproduction Steering Column Covers (Carbon Fiber Available)

Over all looks good when installed. The reason for the three star is I honestly think the install could be easy I fought with the shell for about an hour trying to get so I could start the screws. But that’s the way these are from factory they’re just a pain. But over all would buy again just wish the thing snapped together easier.

Christian W. 3/5

MR2Heaven Reproduction Steering Column Covers (Carbon Fiber Available)

Customer photo review of Toyota MR2 Full E153 Axles with CV joints + LSD/Non LSD Stubs

Experience was top notch. Both axles came very fast since I live in Cali, but I'm sure they'd be fine anywhere around the world. Customer service was able to assist me with best in class customer service. Thank you for an overall great experience!

Glenn E. 5/5 Verified

Toyota MR2 Full E153 Axles with CV joints + LSD/Non LSD Stubs

Customer photo review of MR2Heaven "OEM Shaved" Wiper Cowl - Carbon Fiber Only

Fit almost perfectly. Since it’s not flexible like the broken thin 90’s plastic it will take some finesse to get it in the right spots but shouldn’t be an issue for anyone familiar with carbon fiber or fiberglass. I will need to get longer screws for the ends but I have driven on the highway and it doesn’t rattle or lift at the ends like OEM, so long as you have every other screw in place it doesn’t seem like it’s going anywhere.

Aiden Y. 5/5

MR2Heaven "OEM Shaved" Wiper Cowl - Carbon Fiber Only

Customer photo review of MR2Heaven Heavy Duty Premium OEM+ Leather/Alcantara Seat Covers [Heated Seats Available]

Transformed the car. Old cracked leather covers out, replaced with new. I used zip ties and massaged seat foam to where it needed to be, and the seats feel like brand new. I added some soft foam to drivers side to increase bolstering. Also got the heated seat kit which I'm wiring up to period-correct Toyota heated seat switches in the switch blanks next to fog light switch, for 100% stock look. My only gripe - Was sold as black Alcantara but the center part looks gray... much lighter than rest of car interior, until t-tops leak and get the fabric wet.

Kurt H. 4/5

MR2Heaven Heavy Duty Premium OEM+ Leather/Alcantara Seat Covers [Heated Seats Available]

Customer photo review of OEM Reproduction Heavy Duty Rear Trunk Cargo Tray Boot, Mat, Liner - MR2 SW20

MR2 Heaven is a great resource for an individual who is new to the MR2 community that just purchased a 1993 MR2 Turbo T Top with only 45,000 miles in amazing condition. I have purchased more than a few items already and just received my Enkei RPF1 17x7 & 17x8 Staggered Wheels in Silver to replace the original 15” Wheel because I was very limited to tire selection. All of the items I have purchased from MR2 Heaven are very good quality and benefit the vehicle. Buy with confidence because this resource is one of the best!

Nigel L. 5/5 Verified

OEM Reproduction Heavy Duty Rear Trunk Cargo Tray Boot, Mat, Liner - MR2 SW20

Built on Experience. Driven by Better.

With 20+ years of MR2 experience, an engineering background, hundreds of parts developed, and over 35,000 orders fulfilled, we know the MR2 platform inside and out.

Serving enthusiasts worldwide, we develop hard-to-find parts, OEM+ solutions, and industry-first upgrades using modern engineering tools and advanced manufacturing resources.

Driven by a relentless pursuit of better, a commitment to excellence, and uncompromising attention to detail, that philosophy is reflected in every part we create.

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