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 causes high pressure in a car a / C system?

Also, the condenser should be checked to ensure that there is not an obstruction blocking the condenser’s air flow. High pressure can be the result of loose fan shrouds or air dams. The fans and shrouds should be mounted securely in order to work effectively. Tighten any of the appliances that are not positioned correctly or tightened adequately.

What causes the air conditioner pressure to go up?

An overheating engine radiator can cause the air-conditioning system’s pressure to increase significantly. Heat from the radiator transfers to the condenser and cause the pressure to rise due to the warmer refrigerant. It is possible the space between the radiator and the condenser has become clogged with debris.

What are the symptoms of a bad AC pressure switch?

The most common symptom of a bad AC pressure switch are that you will notice that the AC compressor is cutting on and off rapidly when you are idling your car. These switches between on and off can be noticeable on the engine’s rpm, and you may see or feel fluctuations from it.

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.

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 is my climate control unit no longer working?

It was no longer used after 1999, due partly to unreliability, and partly due to upgrades to newer technology. The most common problems with this vintage of AC Delco climate control systems are failure of ventilation door servos, and failures of the control unit. This document pertains to the control unit.

Why does my GMC 1500 heater not come down?

I HAVE A 2000 GMC PICKUP Z71 THAT THE CONTORL FOR THE TEMPERATURE DOES NOT COME DOWN UNTIL THE TRUCK IS SHUT OFF. THE HEATER CONTOL PANEL WAS JUST CHANGED. ALSO IT HAS AC AND MANUAL CONTROLS … read more

How to recalibrate the HVAC actuator in a GM Truck?

For manual systems it does not matter where the a/c controls are set but if you feel the need to do something, turn the blower switch on (I prefer speed 3) and set the temperature sliders about .5″ to .75″ from full cold. For auto systems, press the auto button, with the key on. Turn the ignition off.

Why is my C-1500 AC not working?

If it’s low enough, the compressor will not even kick in. Just a thought before you start tearing things apart. Thanks. I only have an old R-12 gauge set, so I can’t actually test the refrigerant level.

Why is my AC compressor not turning on?

If the compressor isn’t starting, check the wiring connecting the two units. If it’s a blown fuse or tripped circuit breaker, the search has come to an end.

Why does my GM Truck AC keep blowing out?

The 1995 and earlier have a different circuit board layout, the transistor numbers and concept should still apply but the the locations shown in the video will be different. If you find that the transistor keeps blowing out after replacement, then its because of too much current passing thru due to a short to ground in the circuit.

Why is my air conditioning not working on my GMC Sierra?

While there are a variety of reasons your GMC Sierra 1500 air conditioning won’t work, the most common 3 are a refrigerant leak, an electrical climate control issue, or a problem with the air conditioning compressor.

If the compressor isn’t starting, check the wiring connecting the two units. If it’s a blown fuse or tripped circuit breaker, the search has come to an end.