Heater/defrost problems

[nikwho]

Hello all, its getting close to winter and I want to get this fixed. My '83 has a/c. When the switch is in the a/c position, it blows hard. When the switch is in the heater or defroster position, It blows but only very softly. During recent rain storms I have had to use a towell to wipe off all of the windows. Kind of dangerous. The blower motor slows down noticably so I dont think that its a duct thats disconnected or anything. The a/c is not hooked up. It will not blow hot air when in the a/c position. Any thoughts??? Thanks guys,
Nik

[CaliDude76]

I believe there's a relay that's mounted on the outside of your A/C boot, that im sure determines the juice flow to the blower motor... like when you have it in the "MAX',..or "NORM, BI-LEVEL".. it blows a lot harder when in MAX, then kicks down in the other positions... now I'm no expert,.. but thats what it sounds like to me,.. or what I would check if it was my 84 doing that.. also, I just replaced the blower motor too.. not too costly.. like 20 bucks... might wanna check that too... I'll post some pix of the relay.. (please somebody correct me if I'm wrong)...

another possibility... is it could have a vacuum leak, or cracked hose somehwere... not allowing it to change correctly through all the positions... seeings that the whole distribution box is all vacuum driven....

[CaliDude76]

pix

[nikwho]

your comment about a vaccume leak raised a big old red flag. I have been fighting with many of the vaccume lines. I didn't realize that could be the cause of this

[CaliDude76]

Originally Posted by nikwho

your comment about a vaccume leak raised a big old red flag. I have been fighting with many of the vaccume lines. I didn't realize that could be the cause of this

Yeah... thing is, if you have a weak vacuum coming in from the engine compartment.. it won't work properly..

Don't know if you've ever looked under there.. but there's little vacuum pods that actuate levers and such to flip back from modes.. like defrost, or vent, or heat and such.. plus behind the A/C control head unit itself.. is vacuum actuated... might wanna listen for hissing sounds.. when you have it on... that might help you find a leak...

I know first hand about the vacuum nightmares these trucks can have...more than enough times I've had to trace hoses.. and replace split, cracked, brittle lines.. especially around the carb....(not to mention lines and hoses I've cracked myself fiddling around in there)

makes me wanna pull my hair out sometimes.. when my trucks running rough due to a vacuum leak I was tackling to find..