Over the years, there have been many models of the Cadillac, each with its own unique style and features, but all staying true to the Cadillac brand. More recently, Cadillac has produced cars that are more sporty in appearance. These have smaller, sleaker bodies, and boast a robust line of capability and power.

Because the Cadillac is one of the most popular cars to date, and because it has been around for a long time, car enthusiasts don’t pass up the chance to share valuable information that can serve as technical tips for those who may share a common problem. Below are a few such tips, specific to 1986 and 1987 models.

One problem that seems common among 1986 and 1987 Cadillac is with the blower motor. It often stays engaged even when the ignition switch has been turned off, which can be cause for concern, as this is not supposed to occur.

The power supply to the blower comes from Circuit 761, which is a solid purple wire, and control of the blower comes from circuit 760, also a purple wire with a white tracer. When the ignition is off, and the key is removed, there is no signal on circuit 760. Therefore, only a shorted module could cause the blower to remain on. The following diagnosis procedure will help you determine the cause of failure.

Check the blower motor amperage to see if it is excessive, (20 amts max). This is important because the blower motor can spike, causing a power shortage to the module. The blower should operate at only 20 amps, so if it you find that it is a greater amperage than that, you might consider consulting your car dealer or mechanic to fix the problem. If you feel uncomfortable checking this yourself, refer the problem to the dealer or mechanic, and explain what the problem seems to be.

Another common problem among 1986 and 1987 Cadillacs is the compressor running all the time, even when the a/c/ switch is in the off position. This can be diagnosed by checking the compressor while it is still on. Inspect the vehicle to see if the air gap between the clutch hub and the pulley is set correctly. The air gap should be set to the recommended OEM specification, and spaced evenly around the pulley/clutch hub area. If the gap is closer on one side of the clutch than the other, the compressor may be damaged and should not be used. This condition could cause the compressor to constantly remain engaged.

If this is the case, again, consult your dealer or mechanic to assess and fix the problem.

Easily Repaired Cadillac Glitches

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  • August 26, 2008 at 10:02 pm

    Blower motor and A/C compressor problems plagued a number of GM cars of this period, but especially the “C” and “H” body cars (Cadillac DeVilles, Olds 88 & 98, Buick Electra and LeSabre, Pontiac Bonneville). Any of the above models with C68 A/C are prone to the blower motor issue you outlined and all are prone to the A/C compressor problems. The compressor is mounted in an very exposed area and is subject to damage from road debris. One thing that is VERY important – if any work is done on these cars where the compressor debris shield is removed be sure your mechanic reinstalls it when the work is completed!!

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