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Topic: How to bypass WOT AC cut out switch in 86 TC (Read 3649 times) previous topic - next topic

How to bypass WOT AC cut out switch in 86 TC

Can anyone tell me how I can bypass the AC cutout switch in a 86 TC. Ever since I did the LA3 swap the AC cuts on and off and the only way to get it to work is to turn it off and turn it back on. It happens when I overtake cars on the freeway, and also in stop and go traffic.

I have an aftermarket AC unit that can handle spinning at 8,000rpm's for long periods of time with no issue, so I just want the switch bypassed, so that it doesn't shut off-unless of course turn it of myself.

Can I bypass the switch and where is it?
Motorsport FMIC, Boport 1.5, Boblee header, gutted upper, profiled lower, phenolic spacer, Accufab fpr, LA3, Boport stage 3 big valve head, 57 trim/stage III Perfromance Techniques custom turbo, stinger 3" DP and custom 3"exhaust, AEM wideband, custom aluminum carnk pulley, Merkur custom A/C setup, PA performance high output 3G alt, dual oil catcj cans, Motorsport Valve cover,full Motorcraft tune up kit, 22psi of LOCO!!

How to bypass WOT AC cut out switch in 86 TC

Reply #2 –
I didn't think the 2.3's had a WOT?  I thought it was part of the IRCM?  Anyway, I had the same problem with my fans not working.  I took it to the local stero shop and they wired up a bypass for me.

How to bypass WOT AC cut out switch in 86 TC

Reply #3 –
I know i am going to get HAMMERED on this one but here goes. DONT DO IT. The compressor WOT CUTOUT is their to protect the compressor from over speeding. The reason Ford did this is because the compressor in QUESTION has an RPM LIMIT before it GRENADES. So it was designed to allow the compressor to give out good cold air at low rpm's. Example when stuck in TRAFFIC. So they over speeded it quite a lot. So they designed a cutout circuit. It also drops out to increase HP and reduce the load on the engine for PASSING ETC. WAC pin 54 on most ford ECM'S cuts out the compressor and controls the IRCM on newer TC models. On older ones their is a module behind the GLOVE COMPARTMENT. Your LA3 should restore the AC clutch when the RPM drops. If it does not something is wrong. You can design a circuit to do this very easily. But something is not working correctly with your LA3 Conversion or the ECM is defective. I think if you remove the RED WIRE from the IRCM pin 22 it defeats the WOT feature. Or if you remove the red wire from the ECM pin 54 it also defeats it. If memory serves me pin 54 sends out a ground that deactivates the clutch electronic module. And this in turn drops out the AC CLUTCH. I would advise against deactivating this feature and find the trouble. Thanks
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

How to bypass WOT AC cut out switch in 86 TC

Reply #4 –
Tom, this seems to be a common problem with people who do a PC1 to LA3 swap. My 86 TC does not have a IRCM(black box) like the 87-88 TC. So when I am in stop and go traffic the A/C shuts off and does not come back on. It also does this when revved. I constantly have to turn the switch off and turn it back on.

Anyway, if I pull pin 54 this should solve my problem?
Motorsport FMIC, Boport 1.5, Boblee header, gutted upper, profiled lower, phenolic spacer, Accufab fpr, LA3, Boport stage 3 big valve head, 57 trim/stage III Perfromance Techniques custom turbo, stinger 3" DP and custom 3"exhaust, AEM wideband, custom aluminum carnk pulley, Merkur custom A/C setup, PA performance high output 3G alt, dual oil catcj cans, Motorsport Valve cover,full Motorcraft tune up kit, 22psi of LOCO!!

How to bypass WOT AC cut out switch in 86 TC

Reply #5 –
The module on your car is behind the glove box. It also has the fan relays in that unit. It has 8 wires if i remember correctly and one is for the Clutch of the AC Compressor. I will go on line now to check it out on my All Data. Hang tight.

OK looks like pin 3 is the WOT signal lead from pin 54 of the ECM. So i think if you remove it the AC will stay running. I am not sure if the ECM sends a ground out to operate the clutch or drop it out. A quick test with your trusty test light can confirm that. Either way that is where the cutout is controlled from. Hope this helps. Personally i cant understand why it does not work. Both ECM'S have the WOT going to pin 54. That is a a given. So i cant figure why it does not work. Good luck and remember the WOT CUT OUT is necessary in my BOOK. I had a thought All Data shows a clutch relay for the 5.0 and 3.8. But not for the 2.3?? So i would think if you wired the Cycling clutch switch output lead to the compressor the compressor will run without the WOT FEATURE. I think all the leads are at the combo module behind the glove box. You will have to do some testing. and or install a slave relay. Good luck. I think the Cycling clutch switch on the acspoogeulator can handle the current on the clutch. Not 100% but almost sure it can. If not wire in a slave relay.
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

How to bypass WOT AC cut out switch in 86 TC

Reply #6 –
The wot solid state component is in the IRC, 87evtm which may or may not be different from the 86.

see page 219 of evtm
see page 61 of evtm
both can be found in my evtm link below.

pin54 is called out as red, tells me it may be power. 
The solid state device shown on page 61 (pins 21, 22, 23 of IRC may be nothing more than a transistor.

not sure which pin 3 you mean,
pin 3 at the eec is speed sensor, seems reasonable pin 54 picks the irc wot solid state device when the speed sensor signal is low enough or meets the threshold.  so yes i would agree, integrating a slave relay would be better.

pin 3 at the IRC is a yellow fuse link wire.

How to bypass WOT AC cut out switch in 86 TC

Reply #7 –
NO NO the 86 does not have the IRCM. The 86 has the electronic module behind the glove box. Its an 8 pin module that has the 2 fan relays in it along with the Electronic clutch circuit. Pin 54 of the ECM goes to pin 3 of that module. If he had an 87-88 he would have the IRCM. Hope i explained this correctly.
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

How to bypass WOT AC cut out switch in 86 TC

Reply #8 –
Quote from: TOM Renzo;364651
NO NO the 86 does not have the IRCM. The 86 has the electronic module behind the glove box. Its an 8 pin module that has the 2 fan relays in it along with the Electronic clutch circuit. Pin 54 of the ECM goes to pin 3 of that module. If he had an 87-88 he would have the IRCM. Hope i explained this correctly.

 
So rather than pull the wire from pin 54 I can just cut the wire from pin 3 of the module? Easier to get to.
Motorsport FMIC, Boport 1.5, Boblee header, gutted upper, profiled lower, phenolic spacer, Accufab fpr, LA3, Boport stage 3 big valve head, 57 trim/stage III Perfromance Techniques custom turbo, stinger 3" DP and custom 3"exhaust, AEM wideband, custom aluminum carnk pulley, Merkur custom A/C setup, PA performance high output 3G alt, dual oil catcj cans, Motorsport Valve cover,full Motorcraft tune up kit, 22psi of LOCO!!

How to bypass WOT AC cut out switch in 86 TC

Reply #9 –
Differences in EEC pin usage between 86 and 87. For anybody that wants to theorize why the A/C behaves the way it does when the 87 ECA is plugged into an 86 car.

We will have to know what repinning RDOG did.
 
Pin 2--  86- not used.
______ 87-Brake on/off signal

Pin 3--  86- not used
______ 87- Speed Sensor

Pin 6--  86- not used
______ 87- Speed sensor

Pin 24- 86-not used
______ 87- Premium fuel

Pin 25- 86- Vane Air flow Meter temperature
______ 87- Air Charge Temperature sensor

Pin 27- 86- not used
______ 87- Vane Air Flow Meter Flow

Pin 31- 86- not used
______ 87- Boost Control Solenoid

Pin 32- 86- Boost Control Solenoid
______ 87- not used

Pin 33- 86- not used
______ 87- EGR Shut off solenoid

Pin 34- 86- Tripminder
______ 87- not used

Pin 35- 86- EGR Control solenoid
______ 87- Programmed ride control

Pin 42- 86- not used
______ 87- Kickdown solenoid (A4LD)

Pin 43- 86- Vane Air Flow meter Flow
______ 87- Vane Air Flow meter Temperature

How to bypass WOT AC cut out switch in 86 TC

Reply #10 –
I know all the pinouts, but it didnt help with the Ac. here is the link...

http://www.gt350mustang.com/eecspecsturbo.htm

If I could repin it to make it work correctly, I would, however there is no fix. I'm not the only guy with this issue. So I would rather my A/C never cut out. So should I cut 3 wire going to module?
Motorsport FMIC, Boport 1.5, Boblee header, gutted upper, profiled lower, phenolic spacer, Accufab fpr, LA3, Boport stage 3 big valve head, 57 trim/stage III Perfromance Techniques custom turbo, stinger 3" DP and custom 3"exhaust, AEM wideband, custom aluminum carnk pulley, Merkur custom A/C setup, PA performance high output 3G alt, dual oil catcj cans, Motorsport Valve cover,full Motorcraft tune up kit, 22psi of LOCO!!

How to bypass WOT AC cut out switch in 86 TC

Reply #11 –
Quote from: RDOG;364666
I know all the pinouts, but it didnt help with the Ac. here is the link...

http://www.gt350mustang.com/eecspecsturbo.htm

If I could repin it to make it work correctly, I would, however there is no fix. I'm not the only guy with this issue. So I would rather my A/C never cut out. So should I cut 3 wire going to module?

The O/LB wire from EEC pin 54 to Cooling Fan Controller pin 3 is the only way I can see the EEC has to turn off the A/C.
Cut it and see what happens. It will either fix the problem or the A/C will never run.
You can always splice it back.

Did you figure out the repinning yourself or follow some instructions. There must be something the program in the EEC doesn't like about it's new invironment.

How to bypass WOT AC cut out switch in 86 TC

Reply #12 –
Quote from: softtouch;364672
The O/LB wire from EEC pin 54 to Cooling Fan Controller pin 3 is the only way I can see the EEC has to turn off the A/C.
Cut it and see what happens. It will either fix the problem or the A/C will never run.
You can always splice it back.

Did you figure out the repinning yourself or follow some instructions. There must be something the program in the EEC doesn't like about it's new invironment.


I think  that will work and if it does not see what pin 54 supplies when the AC is running. If its GROUND ground pin 3 of the controller. If its battery supply battery. But i think the ECM supplies a ground to drop out the clutch through pin 3 of the control fan module. Just check it and modify it. Remember those compressors cant take HIGH RPM NUMBERS. They are OVER DRIVEN by quite a lot.
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

How to bypass WOT AC cut out switch in 86 TC

Reply #13 –
im wondering about what your saying, isnt the ratio .75 : 1 (ac pully to crank pully)

not sure is there is a way to mount a new pully on the compressor but that would help alot if it were a larger diameter incase the engine rpm is an issue.  This isnt a fix but it would be a small token of insurance.  An aod car would be more appicable than a stick i think,

How to bypass WOT AC cut out switch in 86 TC

Reply #14 –
Quote from: TOM Renzo;364701
. Remember those compressors cant take HIGH RPM NUMBERS. They are OVER DRIVEN by quite a lot.
This may well not apply to a '86, but on the '87-'88 2.3 the crank pulley is 6" which drives the water pump pulley that is also 6"... The 5" compressor pulley is driven from a 5" pulley attached directly to the water pump pulley, so  drive ratio is 1:1...