I've been searching quite a bit before posting this. Sorry if this is a repeat, but I cannot find another posting like this one.

I have intermittent performance, mostly no performance, with my 740 Turbo Intercooler wagon. 1990. I turn on the heating/cooling/defrost system, and nothing. No blowing. No sound. But, if I go on the interstate, I will feel the appropriate heat/cool/defrost coming out of the vents at high speeds. Not a ton, mind you, but enough so that I can feel it. So, I know that perhaps the thermostat is working, but could it be the fan? Something electrical? Then, every so often, I'll hear some "crack!" while driving and the system will work...with whatever I have on...heating, cooling, defrost, etc. It'll go off in about 10 minutes, and it doesn't blow really strongly, but it does work like that on an odd, off chance. Checked the fuses, and they're fine.

I'm really working on not taking the wagon in for repair. I really want to solve this one between my husband and me, like we've done with other things on this wagon and our 940.

Thanks in advance for any help.