Defroster question

On my 99 Cherokee, with the defroster on, about every 15 seconds I hear a click (like a relay) and the RPM will momentarily drop and the lights will momentarily dim. Also, when this happens, the volt meter drops down to just over 13v.

I tried the other heater settings, but it just seems to be on the defrost.

Dave

It's your AC compressor turning on and off. The defroster setting cycles the AC to dehumidfy the air entering the cabin, to prevent window fogging as defroster-heated air hits the cold windshield.

It's normal on modern cars for the AC to run in the defrost mode.

AZ Jeff said:

It's your AC compressor turning on and off. The defroster setting cycles the AC to dehumidfy the air entering the cabin, to prevent window fogging as defroster-heated air hits the cold windshield.

It's normal on modern cars for the AC to run in the defrost mode.

Click to expand...

Ok, thanks. I've driving my old 87 4-Runner too long, still getting used to this newer car stuff!

Dave

Ok here is another defroster question but about the rear window one.

Somtimes my rear defroster switch works and sometimes it doesn't is there a loose wire or should I check a relay or something?

When it works you can see the light come on and watch it work on the rear window, other times it does nothing.

It an 88 BTW.