skeptic

Long story short - my heater was working fine, blowing air as it should, hot/cold all good. A couple years ago I took out the interior - new carpets, fixed issues, etc. After putting everything back together the heater control was "stuck" in the off position. FF to now - center console is out again and I replaced the heater vacuum control switch that was broke and had jammed the heater off.

Unfortunately, the heater fans will NOT come on. Fuses have been replaced under the dash, electrical connectors on the control switch have been lightly sanded and reconnected, no joy. However, what I did notice is the vacuum line connector fits a bit looser compared to the stock vacuum control switch and I can hear the vacuum leak hissing away.

Before I start trying to figure out what wires to trace, relays to replace, and how to bypass the controls and just get 12V to the blower motor, would a leaking vacuum control switch keep the fans from coming on at all?

jdp6000

It has to work right. Sliding it out of off activates the blower then the hi low takes over.

How is the blower relay on the engine side?

If you put the vaccum connector back on cockeyed it could jam it.

It should not be hissing all the time.

gbvette62

I don't think that a vacuum leak should effect the fan's function.

The vacuum system controls the heater box doors, that directs air to either the floor, dash vents or defroster vent. I can't recall any correlation between the fan switch and the vacuum. I'll try to dig out my 81 Shop Manual a little later, and see if there is any reason why one, could effect the other.

skeptic

It's hissing all the time - I can push it tight and the hissing gets less, but not completely.

My thought is if it was off when it broke, the vacuum leak may not let it go to any of the on positions so the fan will never go on, regardless of the hi/low position. I just don't know if this is wishful thinking or if something else really is broken.

The vacuum connector is on straight, but I think the posts are slightly thinner than the stock one - it slides on/off a lot easier. I'll need to figure out something to fix the leak, but after hooking things up and swapping out fuses then not being able to find my multi-meter a bit of frustration set in and I just walked away.

How can I test the blower relay?

edit: My car has A/C (which lost it's charge 10+ years ago), if that makes any difference.

skeptic

Quick update in case someone searches for this issue in the future - I hate finding threads like this that just die without the fix being posted.

It was the relay. No idea how it happened or how it could possibly every have worked - one of the blade connectors was bent and not going into the connector slot. I don't remember ever taking the relay off, no reason to for anything I've done, but the heater did work in the past...

Hopefully the vacuum leak is resolved as well. I couldn't get a good seal no matter how tight I pushed the connector on, so I bubba'd it a bit by putting a small dab of silicon caulking at the base of the posts. Haven't checked since I left it to dry, but it should be enough to seal it and still be easy enough to pull apart in the future if I ever need to.

FWIW, I pulled a couple fuses years ago when I couldn't figure out a slow battery drain. I thought that was part of why the heater fan wouldn't come on - nope. Turns out the drain was the dome light timer - figured it out by searching this forum, you guys are great.