What causes a GMC CK HVAC unit to malfunction?
This is caused by an open Switched +12V power transistor, or it could possibly be caused by a defective blower speed switch. This is caused by a shorted Switched +12V power transistor, or it could possibly be caused by a defective blower speed switch.
What is the temperature control on a GMC CK truck?
Power is routed back out to Pin 7 through a 3.8 ohm resistor and the Max AC switch, but on a 1500 truck Pin 7 is not used. The Blend (temperature) door control is powered directly from +12V via Pin 5.
Why are the vents on my GMC Sierra stuck?
The most common symptom of course is lack of control over the vent output position and normally it will be stuck in the defroster only position. If it is not currently stuck in the defroster position but you are changing the actuator anyways. make sure that you set the vent position to defrost before starting this procedure. You will see why later.
When was the GMC C / K HVAC unit last used?
This Heater AC Control Unit was used on the 1996-98 line of Chevrolet and GMC C/K Pickups, and on 1996-99 GM Suburbans, Tahoes, and Yukons. It was no longer used after 1999, due partly to unreliability, and partly due to upgrades to newer technology.
Why is the defrost not working on my GM Truck?
My airflow is stuck in the floor position no matter what setting is switched on the dash vent switch. I can’t get defrost or dash vent air to work. Fan settings do work. Also, there is no light coming on when the AC button and/or the recirculating buttons are pushed.
What to do when air blows out of defrost?
Try resetting the HVAC system. I had a similar problem on my 2002 Avalanche. Here’s what I did, and it worked for me. Turn the HVAC system off (turn the blower motor switch to off), and the radio off. Then turn off the truck, and disconnect the battery for 5 minutes. Reconnect the battery, then turn the ignition on, but do not start.
The most common symptom of course is lack of control over the vent output position and normally it will be stuck in the defroster only position. If it is not currently stuck in the defroster position but you are changing the actuator anyways. make sure that you set the vent position to defrost before starting this procedure. You will see why later.
Where does the air come from in a GMC Sierra?
This 2005 GMC Sierra came in with the complaint that the air will only flow from the defroster vents, regardless of where it is commanded to. This Sierra has auto a/c controls and no floor mounted center console.
Where is the AC relay located on a GMC CK?
The AC Relay is located external to the controller. The coil of the AC relay is powered from the ECU, located on the left side of the engine bay. The High Pressure, Cycling, and Lo pressure refrigerant switches also go to the ECU. When all conditions are met, the ECU provides power to the AC relay coil, and the AC compressor clutch is energized.
What kind of engine does a GMC Sierra have?
If the vehicle has the DURAMAX®Diesel engine, refer to the DURAMAX®Diesel supplement for additional and specific information on this engine. Keep this manual in the vehicle for quick reference. Canadian Owners Propriétaires Canadiens
Where is the fuse block on a GMC Sierra?
The fuse block access door is on the driver’s side edge of the instrument panel. Pull off the cover to access the fuse block. Instrument Cluster, DRL Relay, Lamp Switch, Keyless Entry, Low Coolant Module, Illuminated Entry Module, DRAC (Diesel Engine)
Why does my GMC Sierra a / C compressor not work?
Add some freon to it “just one can for now” and see if the compressor will kick in. If it does add freon to it slowly till the high side goes to around 200 and the low side does not fall under 30. If it does not kick in let me know and we can go over he power and grounds and get the a/c to work again.
Is there no power to an A / C compressor?
Went to try the A/C no power to compressor. Bypassed hi and low pressure switches, no power to compressor. Swapped out starter and A/C relay, no power to compressor ??
Why is my a / C not working on my 1998 Silverado?
Recently bought truck 1998 silverado z71 4×4 dually. A/C was not working, I determined that the compressor was bad. Replaced compressor, condenser, inline filter, freon & oil. Went to try the A/C no power to compressor. Bypassed hi and low pressure switches, no power to compressor.
Where is the a / C relay on a GMC Sierra?
Can you see if you have voltage to two pins for the a/c relay, it is in the fuse box you just checked the fuses in. Make sure the engine is running and the a/c is on, on the control deck. I have power at two of the four pins in the relay, the fuse that does not have power is chmsl right under frt HVAC.