the ac was working fine, but now only works every now and then. pressure is good. fuse under dash is good, relay under hood is good. clutch on compressor doesnt get power all the time, so im thinking its a short somewhere or the ac button itself is going bad, its the kind that has the recirc ac and def all in one. has anyone had any issues or or know where i should begin looking at, im stumped, both me and my grandfather are ac mechanics and cannot figure it out. any and all help will be greatly appreciated

 

Does the condenser fan always start when you press the button? Does the engine idle speed always increase?

I'd swap the relays around anyway to test, I think you can substitute the rear defogger one for the compressor.

 

ive switched the relays around and the relays are good, and the engine idle does not increase all the time

 

thats whats making me think its something in the control where the 3 buttons are

 

When you press the button does the light in the button come on, and does the condenser fan run?

The thing with the 3 buttons just drives a computer in the main part of the control panel which has the ***** for the fan and temperature. There is a self-test for the computer in the service manual. If the light on the button comes on but the condenser fan and compressor don't start, the problem could also be the evaporator temperature sensor.

 

The self diagnosis function of the 2000 heater control panel only tests the air mix control circuit.

If the condenser fan works fine, the refrigerant pressure is good, and only the compressor clutch fails to engage intermittently and when this happens does not cause the idle to increase, then you may have a faulty pressure switch or ECU problem or a bad wire/connector terminal in the ECU/pressure switch terminal.

 

i did a auto tranny swap to a manual and didnt have a ecu for the manual tranny, do you think this could have anything to do with it, i wouldnt think so but maybe someone can chime in, and where is this pressure switch located at

 

The signal to engage the A/C compressor does go through the ECU but it'd be the same for auto or manual. If the idle speed is abnormally low, the ECU will refuse to engage the compressor in order to prevent stalling out. Other than that rule, once the ECU gets the signal (from the control panel and through the pressure switch), it will just bump up the idle and about 1/2 second later actuate the compressor relay.

The pressure switch should be mounted on the condenser, maybe in some models it is on the receiver drier. If the pressure is normal it is a closed circuit. Negative logic is used, you should measure near battery voltage on the switch wires when the A/C is off, and near ground when it is on.

Please tell us whether or not the condenser fan comes on and also whether the light in the button comes on.

 

yes the condenser fans work, ive switched around the relays under the hood and their good, i juse ordered the ac recirc and defogger buttons, so they should be in tomorrow and i will keep it updated and if that dont fix it ill replace the pressure switch, my guessing is its gonna be one of the two

 

Cancel the buttons order. They are fine if the condenser fan runs.

Don't replace parts randomly. Test continuity of the pressure switch and voltage at the ECU from the clutch relay.