A/C won't restart after full throttle
 

Help: A/C shuts down restarting car required

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When I go full throttle my a/c shuts down (blows warm) The only way to reset it is to park, shut the engine off, and restart the car. Manually shutting off a/c and turning back on does not reset it when the car is running. I have to restart the engine to have a functioning a/c again. If I do not go full throttle it will continue function normally for the entire drive. Could it be a bad relay? If so where would I find it.

Thanks

I can't be the only one this happened to, can I? I see 72 have viewed this post but no suggestions as to how to remedy the problem. I would be happy to just bypass the A/C cutoff and have the A/C not turn off at wide open throttle. The fix is probably just a five dollar relay or switch but I have no idea where to look. It think it has to be electrical as it resets at restart of engine.

The forum and web are no help so far.

Please help

I haven't seen this mentioned before. Only thing I can suggest is download the FSM and do some troubleshooting.

I think mine did the same thing to me this summer. Didnt really think much of it at the time. If you have uprev I believe you can override the disengage TPS trigger.

does the ecu shutdown power to the a/c compressor at wot? some cars are programmed to do this. if so, then it does sound like a bad relay or switch.

Yes it does, most cars do it infact. I believe its to protect the ac pump as well as give you all the available hp when you need it.

After looking at the service manual (very limited informations).
Im gonna copy and paste the information here, you can find this information @ HA-5

System Description INFOID:0000000004507068
REFRIGERANT CYCLE
Refrigerant Flow
The refrigerant flows from the compressor, through the condenser with liquid tank, through the evaporator, and
back to the compressor. The refrigerant evaporation in the evaporator is controlled by an externally equalized
expansion valve, located inside the evaporator case.
Freeze Protection
To prevent evaporator from freezing up, the evaporator air temperature is monitored, and the voltage signal to
the A/C auto amp. makes the A/C relay go OFF and stop the compressor.
REFRIGERANT SYSTEM PROTECTION
Refrigerant Pressure Sensor
• The refrigerant system is protected against excessively high- or low-pressures by the refrigerant pressure
sensor, located on the liquid tank. The refrigerant pressure sensor detects the pressure inside the refrigerant
line and sends the voltage signal to the ECM if the system pressure rises above, or falls below the specifications.
• ECM turns the A/C relay to OFF and stops the compressor when the high-pressure side detected by refrigerant
pressure sensor is following conditions;
- Approximately 3,120 kPa (31.8 kg/cm2, 452 psi) or more (Engine speed is 1,500 rpm or more.)
- Approximately 2,740 kPa (27.9 kg/cm2, 397 psi) or more (Engine speed is less than 1,500 rpm.)
- Approximately 120 kPa (1.2 kg/cm2, 17 psi) or less

so you can have faulty pressure sensor, low on refrigerant, relay, clogged or crushed high-pressure pipe located between compressor and condenser.

I would hook up a manifold gauge to check the high/low side pressures and go from there. This is first thing I do to customer vehicles with a/c problems. Hook up an a/c machine with manifold gauges built in, I can figure it out right away whats wrong with the customer's vehicle.

Use REFRIGERATION SYSTEM SYMPTOMS under HA-7 and HA-8 to diag with a manifold gauge.

I hope this helps....

If you can get pressure readings and post in here, I can help you with diag.

I need high/low pressure readings @ idle and @ 2-3k rpm

I don't think our cars have this feature. Vehicles with small displacement engine might have this feature, but not for high hp vehicles.

I'm not sure what parameters it looks at (may be in the FSM), but the car does turn off the A/C compressor when you give it a lot of throttle. Most (all?) cars I've owned did. I've always assumed it was to get rid of the extra load when under hard acceleration, but don't know for sure.

Thanks for the responses, it seems it only happens when I flog it hard enough to get the rev limiter shift light.