No heat. Compressor was red hot.

BlownSix

Registered User
I was driving home tonight with the heat on and I began to notice a burning smell. I thought it was another car or someone burning something. I thought this until I got stuck at a red light and saw the smoke coming out from under my hood! :eek::mad:

I pulled into a parking lot and popped the hood. I didn't see anything that looked like it had been on fire. So, I started the car and turned on the heat. After a few minutes I noticed that the front of the a/c compressor (behind the pulley maybe? It was dark and my flashlight decided to die :cool:) was RED. and I mean RED. I shut it off and let it cool down. Re-started w/o the heat and it runs fine.

So, my question is, can I run an a/c bypass with a shorter belt and still have heat? I've searched and this is basically what I've come up with. But I just want to make sure b/c it's my DD and it's going to be COLD at night this week.

Thanks!
 
You can get an a/c delete. I think they are $30. And i think your stock belt will work. Did you try unplugging the wires to the a/c? It sounds like you climate control is engaging the clutch on your a/c compressor. I would try that first. Maybe in your driveway with a close eye on it ;)
 
just unplug the compressor, plug behind pulley. the atc was prolly kicking the ac on for defrost or to keep the car at a certain temp. as long as the ac clutch isn't draging you'll be good.
 
and by the way, sounds like thats one strong grippie belt. your compressor is prolly locking up so when the clutch tries to engage it just slips and gets hot. i had a compressor lock up and stall the engine at idle.
 
Thanks guys :) I'll go out and unplug that after I have my coffee and wake up a bit. I really hope that's all I have to do. This is not a good time for things to start breaking.
 
On cars with "climate control" systems, the AC compressor can kick in even if not on defrost. They work with a blend door to blend cool with warm air to achieve the temperature called for in the cabin.

With the A/C compressor disconnected, you may need to switch to manual control for the climate control, as it won't get enough cold from the evaporator side for the blend door to do what is necessary so it'll stick the fan at either too high or to low.
 
Thank you Mike :)

I unplugged the compressor and turned on the heat. I *think* I had it on Auto and after letting the car warm up, I did start to feel some heat coming out of the vents. So, it seems like I'll be alright. Hopefully.

I do have another problem that I haven't chased down yet. When I have the heat on (doesn't matter if it's in Auto or manually set) not much heat blows out from the vents. I can hear the blower going full blast but not much heat is being forced out. I searched a few weeks ago on here and a few people said a filter or something underneath the cowl gets clogged up with leaves/pine needles. I haven't investigated to see if that's my actual problem yet.
 
I had an alternator lock up one time...alt caught on fire, pulley sheared off busted up the radiator...one thousand bucks later I we back on the road-this was a 1989 5.0 chevy caprice
 
I do have another problem that I haven't chased down yet. When I have the heat on (doesn't matter if it's in Auto or manually set) not much heat blows out from the vents.

Inside the HVAC box there is a blend door. This door is essentially a flapper valve that creates a path for the air to flow either over the heater core, or the A/C evaporator. When heat is called for, the blend door should move to restrict air flow through the evaporator so that most of the air goes through the heater core.

If you are not getting enough heat, there are a few things to check.
#1 - make sure your coolant is full. Low coolant can lead to not enough coolant to flow through the heater core resulting in low heat. Also, a thermostat stuck open could limit how much heat you have.
#2 - Make sure the heater core isn't blocked. If the car has a history of poor coolant maintenance, "gunk" can build up in the heater core causing insufficient coolant flow through the unit. The only fix is to try and flush the heater core with a pressurized treatment, or replace the core.
#3 Check and make sure there are no vacuum hoses cracked or disconnected under the dash. The blend door motor is operated by a vacuum motor. If it looses vacuum, it won't move fully. The vacuum motor can also fail.
#4 And finally, there could be debris inside the HVAC box that falls in over time. A stick or some debris could be preventing the blend door from moving through it's full range resulting in minimal heat.
 
Blend door

Inside the HVAC box there is a blend door. This door is essentially a flapper valve that creates a path for the air to flow either over the heater core, or the A/C evaporator. When heat is called for, the blend door should move to restrict air flow through the evaporator so that most of the air goes through the heater core.

If you are not getting enough heat, there are a few things to check.
#1 - make sure your coolant is full. Low coolant can lead to not enough coolant to flow through the heater core resulting in low heat. Also, a thermostat stuck open could limit how much heat you have.
#2 - Make sure the heater core isn't blocked. If the car has a history of poor coolant maintenance, "gunk" can build up in the heater core causing insufficient coolant flow through the unit. The only fix is to try and flush the heater core with a pressurized treatment, or replace the core.
#3 Check and make sure there are no vacuum hoses cracked or disconnected under the dash. The blend door motor is operated by a vacuum motor. If it looses vacuum, it won't move fully. The vacuum motor can also fail.
#4 And finally, there could be debris inside the HVAC box that falls in over time. A stick or some debris could be preventing the blend door from moving through it's full range resulting in minimal heat.

Actually the blend door is moved by an electric motor Which can burn out. Good luck finding a new one, working used ones are getting hard to find. When mine burned out, I had to disconnect the A/C clutch to get heat and defrost back just so I would be able to go to work.
MikeH
 
Update: The belt snapped today when I got to work. The car has been making a weird noise, hard to explain. I think something happened with the compressor when it went out and it was wobbling a little and that caused it to snap my belt. What length belt do I need to completely bypass the compressor?

Thanks guys :eek: Been a crappy week.
 
Okay, I found a thread on here that says a 55 3/4 belt will work to bypass the a/c with a little rerouting. Sound right?
 
Okay, I found a thread on here that says a 55 3/4 belt will work to bypass the a/c with a little rerouting. Sound right?

Yeah or 56". But you have to modify the tensioner next to the alternator. And preferrably get a ribbed pulley for the tensioner too.
 
Thanks everyone. I've managed to locate a cheap used compressor and just replace that and not have to modify anything.
 
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