I have a 94 EXR, since I have had it (3 years) the AC hasn't worked. I got my mechanic to check it out his findings were that the system is good as in it keeps charge, the freon level is good, the compressor is good, and the compressor relay is also good.

The strangest thing is that when the ac switch is bypassed near the ecu, the system runs, however it stays on all the time and eventually starts to purge as the safety switch is not working during the bypass. I have switched the ecu with 2 other accords and it still doesnt work. My mechanic is constantly saying it is something to do with the ecu.

Has anyone else experienced these symptoms or come across similar issues?

 

Between the ecu and a/c switch, there is an a/c pressure switch (safety switch) and an a/c thermostat. If system works when you bypass these two componet, one of these two may have problem. First check if the wire connections are ok on these two componets.

 

Thanks, I will check those connections. Also is the a/c switch simply to turn the system on or off?

 

When a/c switch is turned on,
if the fan switch is on the off position, the system will be shut off.
if the refrigerant pressure is very low or very high, the system will be shut off by the pressure switch.
if the a/c thermostat detects the very low temperature, the system will be shut off.
Anyhow, The a/c switch can simply turn the a/c system off. But, it can not simply turn the system on because there are other controls in the system.

 

I have a 1997 Accord and my air conditioner is blowing hot air kinda like the heater. It's not just engine heat, it's very warm. Someone told me there is switch in the engine to switch on the A/C. Is this true?

 

If you already turned the temperature controller all way to cold (left most), pull the **** out to check if it is broken. A broken temperature controller **** will not be able to shut off the heater core. If the **** is ok, look for the heater valve under hood. Looking at the passenger side under the intake air duct, you will find two coolant hoses which lead to firewall. The heater valve is on one of these hoses. Manually turn the heater valve towards front of the car to full off position and you will be able get cold air as long as your air conditioning is working.

 

Thanks for the info. I will try that. Is it possible that the mechanic accidently hit this valve when replacing the timing belts and other stuff?

 

That post wasn't very clear. I recently had the timing belt and head gasket and a few other things done. The A/C starting throwing heat after this.

 

I spoke to my mechanic and he checked the pressure switch and the a/c thermostat. Are there any other components that could be causing the problem? Particularily a bad signal from the ECU?

 

It is true that bad ECU signal will cause A/C problem. However, you mentioned you have switched 2 other ECUs for testing and both had the same result. It is very rare that 3 ECUs have the same problem.
How did you bypass a/c switch NEAR ECU?
You probably need to do a test by yourself.

A/C Pressure Switch Test:
When ignition switch is OFF, disconnect a/c pressure switch 2p connector. Check for continuity between the two terminals of the a/c pressure switch. If there is no continuity and the system pressure is right, the a/c pressure switch is bad.

A/C Thermostat Test:
You probably need to remove glove box to reach it. Jump the BLU/RED wire terminal to ground. Start engine and both fans should run and compressor clutch should engage. Otherwise, the A/C thermostat is bad.

A/C Diode Test:
You may need to test the a/c diode. It is located above the left kick panel. Just make sure it only passes current in one way.

 

My issue doesn't seem to be heat related - when the a/c works it works great. Seems to be no reason when/why it decides to work or not. Where is the a/c pressure switch and connector and how do I know by looking what the Thermostat behind glove box looks like? Been all over this car but haven't benn here! Thanks!

 

does anyone have a picture of the internal thermostat box and switch?

 

How long does your system run before it stops? Pressure switches come to mind.