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Squiggle Dog · #**198** 02-25-2021, 05:18 PM

I can never seem to keep the air conditioning in this car working for very long. It's been one thing after another. Once again, as of June 2020, it wasn't blowing cold.

The auxiliary fans weren't coming on and I could hear one of the relays making clicking noises and then sometimes the fans would run intermittently. I tested the refrigerant charge and added some to see if it would make a difference, but it did not.

I tested the various system components and ultimately found it to be a bad wire going to the auxiliary fan pre-resistor. The pre-resistor happens to be located underneath the brake booster, under some wire looms, and back behind a false firewall.

I feel like I do not have hands small enough to be working on this car! Fortunately, I fixed the problem. I bypassed the pre-resistor by attaching the two wires together, since its function is to make the auxiliary fans run at half speed when the air conditioning is on. Full speed is better!

So now the fans always run at full speed when they are switched on, and the air conditioning feels nice and cold.

I had to pull away part of the false firewall so I could access the pre-resistor (the part that fails always has to be the hardest part to replace, doesn't it?).

The pre-resistor is way down there at the bottom, hidden underneath the brake booster.

Here it is. The pre-resistor was loose on one end.

One of the rubber insulators had melted off, and the wire going to the same side got hot and burned. The coil inside the pre-resistor gets red hot and leaves gather in this area, which starts fires. I cleaned out many leaves and a rat's nest from there.

With the one end of the pre-resistor being loose, it would also allow for the screw at the bottom to ground out against the metal frame.