97 GP manual HVAC blows only hot air

[jem270]

I have the manual HVAC control unit. The only air that comes out of the vents is hot air. It started this right after I turned the defroster on with the temperature control on high. Now the a/c won't cool.

Going to and from max mode makes the door behind glove box open and close
All blower speeds work
Compressor engages when a/c is turned on
Air control works as air will divert to various outlets
HVAC control and DIC/HVAC fuses are OK

It appears that the heater actuator door is stuck open or the HVAC head unit is defective. I need to remove the HVAC head unit to test it and check the connections.

Do I have to remove the entire trim panel around the dash to get it out? The service manual says I need to drop the steering column also.

Service manual also says to backprobe the LH Electric Actuator connector. I can’t find a diagram of where it is.

Service manual also says to check for a binding air temperature valve. I don’t have a diagram for it either.

Has anyone got any advice on doing all this?

[BNaylor]

Is this the manual single or dual zone climate control system?

[jem270]

I believe it is the manual single zone. It has the three knobs with the fan on the left, the temp control in the middle and the vent selection knob on the right.

[jem270]

RPO is C60. Here is a diagram. It is the one on top.

[jem270]

Here is what I found in the service manual for the C60.







I just can't find a diagram or picture of the LH Electric Actuator or the Air Temperature Valve.

[BNaylor]

Yeah I see it is the single zone. In '97 there was the manual single, manual dual zone and CJ2 dual zone ACC. You only have one temperature actuator and needless to say it is located under the driver's side of the dash, left of the center part so not that easy to get to but can be accessed with patience. It looks like it is 50/50. Either the climate control head unit or the temp actuator. I should have some documents like GM wiring diagrams I can send you so let me know.

[jem270]

I found this site that shows how to remove the dash. Looks much easier than the instructions in the service manual. I will take it off and take a look around and see if I can identify the parts.

http://www.carstereohelp.com/stereor...andPrixSt2.htm

[jem270]

Taking the dash out was not that bad. Probably about 30 minutes.

I did step 1 (backprobed Heater-A/C control) and got 1.4 volts at the cold side and it gradually went up to 10.5 on the hot side. I assume that the control is OK.

I could barely see the LH Electric Actuator. It is almost directly above the gas pedal. After I put everything back together I started thinking about this part. I am thinking it is the culprit. I do hear a noise when I move the temp control. I didn't see anything move on the actuator though. Here is a picture of the actuator. Is the part circled in red supposed to move? Mine did not appear to move. Sounds to me like I need to replace the actuator if that part is supposed to move.

Any thoughts?

Where would be a good place to buy this part?

[jem270]

I just found this TSB. I hope it is not my problem.



#73-11-03 Air Temp from HVAC Outlets Does Not Change Or Blows Cold

SUBJECT: AIR TEMPERATURE FROM HVAC OUTLETS DOES NOT CHANGE OR BLOWS COLD (REPLACE TEMPERATURE VALVE DOOR)

MODELS: 1997 BUICK CENTURY, REGAL 1997 CHEVROLET CORVETTE, VENTURE 1997 OLDSMOBILE SILHOUETTE 1997 PONTIAC GRAND PRIX, TRANS SPORT

CONDITION:
SOME OWNERS MAY COMMENT THAT THE AIR TEMPERATURE FROM THE INSTRUMENT PANEL AND HEATER OUTLETS DOES NOT CHANGE OR BLOWS COLD.

CAUSE:
THE TEMPERATURE VALVE DOOR SHAFT MAY BE FRACTURED ON SOME VEHICLES CAUSING STICKING OR NO MOVEMENT OF THE DOOR. THIS CONDITION MAY SHOW UP ON RPO CJ2 SYSTEMS AS A DIAGNOSTIC CODE B0446 OR B0441. THE RPO CJ3, C60 AND C41 SYSTEMS DO NOT HAVE THE CAPABILITIES TO SET DIAGNOSTIC CODES. VERIFICATION OF THIS CONDITION CAN BE DONE BY REMOVING THE TEMPERATURE VALVE MOTOR AND PHYSICALLY HAND TURNING THE SHAFT TO DETERMINE TEMPERATURE CHANGE, BINDING OR LOSS OF FUNCTION.

IMPORTANT:
RPO CODES ARE LOCATED ON THE SERVICE PARTS IDENTIFICATION LABEL.

CORRECTION:
REPLACE THE TEMPERATURE VALVE DOOR.

PROCEDURE -
1. FOLLOW THE A/C EVAPORATOR CORE REPLACEMENT PROCEDURES IN SECTION 1B OF THE APPROPRIATE SERVICE MANUAL.
2. ONCE THE CASE IS SPLIT APART, THE TEMPERATURE VALVE DOOR WILL BE VISIBLE IN FRONT OF THE EVAPORATOR.
3. BEFORE REMOVING THE DOOR(S) IN BOTH SYSTEMS, TURN DOOR(S) UPWARD PARALLEL WITH THE EVAPORATOR AND NOTE THE DETAIL IN THE SEALS FOR INSTALLATION OF THE NEW DOOR(S).
4. THE DUAL ZONE (CJ2, CJ3) DOOR CAN BE REMOVED BY LIFTING THE SHAFT AT THE CENTER TO DISENGAGE THE TWO (2) PIECE DOOR.
5. ON THE SINGLE ZONE (C60, C41) DOOR, CAREFULLY SPREAD THE CASE AND SLIDE THE DOOR TO THE SIDE EXPOSING THE SHORT END OF THE SHAFT AND LIFT OUT OF CASE.
6. INSTALL THE NEW TEMPERATURE VALVE DOOR REVERSING THE PRIOR PROCEDURES.

IMPORTANT:
SEALING OF THE CASE IS VERY IMPORTANT, THEREFORE SEAL KIT P/N 52478813 (KIT 1) MUST BE ORDERED AND ALL OF THE SEALS INSTALLED ANYTIME THE CASE IS SEPARATED FOR A REPAIR.
7. FOLLOW THE A/C EVAPORATOR CORE INSTALLATION PROCEDURES IN SECTION 1B OF THE APPROPRIATE SERVICE MANUAL.
8. ONCE THE INSTALLATION IS COMPLETE, CYCLE HVAC SYSTEM MODES FOR PROPER OPERATION.

PARTS INFORMATION:
P/N DESCRIPTION QTY. === =========== ====
52469884 VALVE, TEMP (C60, C41) 1
52477971 VALVE, TEMP KIT (CJ2, CJ3) 1
52478813 SEAL, HVAC CASE (KIT 1) 1

[jem270]

There is something else I just thought of. In the old days, if the R12 was low, then the compressor would not kick on. Is this system the same? Can I assume that there is enough 134 if the compressor kicks on?

I ask because when I first crank up the car in the morning, I get heat out of the vents. If I turn the temperature dial toward heat then the air feels hotter. Shouldn’t I get a little cool air until the engine warms up?

When I get home I will crank it up and feel the refrigerant lines in the engine compartment to see if one is hot and one is cold. Should that tell me if enough 134 is in the system?

[jem270]

I cranked the car when I got home. It is sprinkling rain. I turned the control on Max and had the blower on high. The air coming out of the vents felt like outside air. I felt the a/c lines under the hood and both of them felt cold. It appears that the system still is full of 134.

After a few minutes, the air coming out of the vents started getting warm. I switched to the defrost and the air coming out of the defrost was warm even with the a/c button pushed.

I don't understand how the air flow is vented in the dash. When I turn the a/c on does the vent for heat close? If so, then it sounds like the actuator is the problem.

Any and all comments are welcome.