T-Bird Air Conditioning problems

I am new to the forum and need. Have a '97 T-Bird with air prob. It is manual (not semi-auto). Air has been working off and on but finally quit. I changed the low/high pressure switch and changed a/c switch inside the car but still got hot air. Hot wired the compressor from battery and get cool air so problem can't be in compressor. Can you guys give me any suggestions what to try next? Thanks, Darrell Honeycutt

Welcome to the forum Darrell. At the pressure switch see if you have 12V on pin 1 (PK/LB) and 3 (R/Y) wires and 0V on pins 2 ((BK) and 4 (T/LG) with the engine running. If these check out then the two other components that determine if the compressor clutch is engaged are the PCM and Constant Control Relay Module (CCRM). The CCRM is located between the air box and the radiator support and has a 24 contact pin connector. One side has contacts 1 - 12 and the other side has 13 - 24. The PK/LB wire from the pressure switch goes to pin 21 on the CCRM so see if you have 12V at this point also. Pin 23 (BK/Y) is the output of the CCRM to the AC clutch and should have 12V. If it does then you have a bad connection between the CCRM and the AC clutch. Let me know what voltage you get on pin 22 (PK/Y) of the CCRM. With the engine OFF and using an ohmmeter, see if there is very close (< 0.3) ohms from the AC clutch wire (GY/W) and a good ground connection. This is the return path for the AC clutch. If the answer is no then there is a bad connection between the AC clutch and the CCRM pin 16 (GR/W). When you jumpered the AC clutch did you just connect 12V to it or 12V and a return wire? Was it still connected or did you have the connectors unplugged?

Thanks so much for the help. I am going to check all this out and get back with you. I appreciate it very much. Will let you know the results as soon as I can get it done.

Ok, I have tried what you suggested and here are the results:
Low pressure switch pin #1 pk/lb wire: 11.14 volts
High pressure switch pin # 3 r/y wire: 11.11 volts
ov on black # 4 with engine running: 13.33 volts
CCRM # 21: 11.40
#23: .043
#22: .047
AC clutch wire gray/white has .02 oms

When I jumped the A/C clutch I used a battery and ran both hot and ground to a/c clutch.

Thanks! What do you reccomend now?

Darrell, You have the correct voltage going to the CCRM (21=11.4V) but no output (23=0V). Go to an AutoZone or other parts store that will read the codes from your PCM and let me know what you get.

Had a guy to use diagnostics computer to test PCM-no codes were found. Ran various tests. Throttle ok through all positions.

The wide open throttle relay read "on" --the (w.o.t.) feeds through PCM to cut off compressor.

This is what we found and would really appreciate help from you as to what the problem could be.

Thanks, Darrell

Where are you getting the reading that the WOT relay is on?

The guy used the diagnostic computer hooked to the OBD II connector and it showed the W.O.T. relay on.

Haven't heard a reply.....do you think this problem could be in the PCM?

Sorry it took so long to respond. I was trying to find out more about the WOT circuit but haven't had any luck. I don't know if the TPS signal is what is used to tell the PCM that the throttle is wide open, The factory manual just shows the relay and the PCM as being solid state devices with no internal circuitry to show what turns the relay on and off. You don't have any trouble codes saying there is a problem with the TPS so I am assuming there is nothing wrong with it. You said you had 0.047V on pin 22 of the CCRM. I am guessing that this is the WOT signal from the PCM.See if this voltage changes at all as you vary the engine speed. Mash the pedal to the floor for a second while someone watches the meter to see if the voltage changes. If the voltage does go up to around 12V with WOT then I would say the relay is bad and you will have to replace the whole CCRM. Let me know what the voltage does on pin 21 also. If it was my car and the voltage didn't change on pin 22 then I would cut the wire in a place that is easy to get to so you can splice it back together. Take a resistance measurement from both of the cut ends of the wire to a solid ground location. Let me know what you get for readings. Attach a 10K ohm resistor to the wire from the PCM and connect the other side of the resistor to a solid ground location. Connect your voltmeter across the resistor and while repeating the test see if you get a voltage drop across the resistor. If the voltage does change now then I would replace the CCRM. If it doesn't change then I would connect one side of the resistor to the wire end going to the CCRM and the other end to 12V to see if the AC clutch engages. If the clutch engages then something is wrong with the WOT circuitry in or before the PCM. I'm sorry I can't give you a straight answer on this but that is what I would do if it was my car. If you can get another OCM and CCRM out of another 'Bird you may want to go that route or spend about $30 on one of the "ask a Ford mechanic" websites. If you do try the tests, please let me know the results.

Thank you very much for your help. I will run this test and get back with you and let you know what the results are. I am confused as to the OCM...we have not talked about it.....just the PCM. Did you mean the PCM??
Thanks! Darrell

Pcm!

Sorry it took so long to get back on here but due to all the confusion we had, and limited knowledge about the parts, we decided to ask a Ford mechanic online which was the best way to go. He said "If the throttle sensor is ok and the computer gives out a "WOT ON" then the computer is bad internally because it uses the throttle position signal to activate the WOT ON. For some reason the computer is signaling the AC cut out relay for no reason." He said to replace the PCM (Power Control Module) which is what we did and it solved the problem!

We sure appreciate your help because we could have never known what to tell him had we not gone through the series of steps you had us do. thanks again for all the help!
Darrell

Thanks for letting us know how you made out.