91 SSE Climate Control Problem

[thumpr77]

The electronic climate control in my 91 bonneville sse isn't working properly. The heat only comes out hot when it is set to the highest temp and the fan keeps shutting off or not coming on at all. Usually in the cold mornings the fan works fine but once the engine heats up it shuts off and won't come on again, or if I shut the car off warm it won't come on again. Turning it on and off does not help. I recently changed the coolant thermostat because the engine wasn't warming up and the heat wasn't getting very hot. The new thermostat is the correct one and solved the warming up issue, but having the heater fan not come on is freezing me out. Any help would be greatly appreciated. I don't know if there is an interior thermostat or not and can't find any info.

[ricksza]

Check out this TSB it might apply:
CLIMATE CONTROL BLOWS COLD AIR DURING EXTENDED IDLE #90-1-8 - (02/02/1990)
Models Affected: 1989-1990 BONNEVILLE MODELS

A condition may occur on some 1989 and early 1990 Bonneville models with C68 air conditioning where during extended idle, the ambient sensor will be influenced by radiant heat from the radiator.

If this condition occurs, the exterior temperature display on the A/C control head will show a much higher reading than true ambient temperature. The false higher reading may cause the system to blow cold air cooling the vehicle interior below the requested temperature.

IMPORTANT: This condition will be apparent ONLY on extended idles generally longer than three (3) minutes. The system will return to normal operation again with the vehicle in motion.

To correct this condition the ambient temperature sensor should be relocated to the center support bar using the following procedure:

1. Remove radiator grille to headlamp mounting panel filler

2. Remove ambient sensor and bracket.

3. Remove ambient sensor from bracket and discard bracket.

4. Remove "J" clip from ambient sensor attaching hole.

5. Remove screw through the retaining tab on the P/S cooler line located on the center support.

6. Attach the ambient sensor and the P/S cooler line bracket to the center support using the original bracket attaching screw (see Figure for location and indexing of sensor).

7. Route sensor wire along center support.

Figure 1

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.



GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
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Document ID# 254013
1990 Pontiac Bonneville