Topic: heater control
in Forum: C3 Q&A with Dave McLellan
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Hey i am new to the site and have just got my first vet a 1981 coupe i seem to be having problems with my defrost air and heater air and vent air coming out the correct place when you set the selector switch to heat or defrost or vent it stays allway blowing out at your feet on the passenge side and maybe every once in awhile it will come out in the correct vent i was thinking that it must be the flapper door in the duct work not responding to the setting what controls the flapper door in the duct work i mean i have air moving just not comming out the correct areas and i noticed it in the ac mode also the ac work it just comes out at the passengers feet nice feeling feet lol :-) any help would be great Thanks Brent Rogers
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Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Welcome to C3VR, Brent!
Sounds like you have a vacuum problem there. Normally, the "default" setting for the flapper door is defrost, meaning it will blow out of the defrost vent if no vacuum is available. However, if the problem is with the vac. control at the console selector switch, it could send vac just about anywhere.
You would need to first verify a good vacuum source/signal getting to the switch from the engine. There should be a vac. line going thru the firewall somewhere to the pass side of the wiper motor. This line provides the vacuum for the HVAC system. Make sure it is connected to the engine/intake manifold. If that line os good, then you'll need to dig under the shift console to get to the heater control switch, and check for a good vac sig. there. The vac. connector at teh switch is known for deteriorating over time, so that could be the source of a vac. leak, which could cause the problem you have.
If the vac control switch, and the connector is good, then it's time to go hunting up under the dash for the vac actuators for the mode doors, and see if all the hoses are connected.
It's a time consuming job, but ya gotta start somewhere!
Also, if you haven't already, get yourself a Factory Service Manual for your car. That will have all of the info you need to work on you car as you get started in repairing anything that is in need. The manuals have all of the wiring, and vacuum diagrams, which makes finding problems like this much easier!
hth!
Sounds like you have a vacuum problem there. Normally, the "default" setting for the flapper door is defrost, meaning it will blow out of the defrost vent if no vacuum is available. However, if the problem is with the vac. control at the console selector switch, it could send vac just about anywhere.
You would need to first verify a good vacuum source/signal getting to the switch from the engine. There should be a vac. line going thru the firewall somewhere to the pass side of the wiper motor. This line provides the vacuum for the HVAC system. Make sure it is connected to the engine/intake manifold. If that line os good, then you'll need to dig under the shift console to get to the heater control switch, and check for a good vac sig. there. The vac. connector at teh switch is known for deteriorating over time, so that could be the source of a vac. leak, which could cause the problem you have.
If the vac control switch, and the connector is good, then it's time to go hunting up under the dash for the vac actuators for the mode doors, and see if all the hoses are connected.
It's a time consuming job, but ya gotta start somewhere!
Also, if you haven't already, get yourself a Factory Service Manual for your car. That will have all of the info you need to work on you car as you get started in repairing anything that is in need. The manuals have all of the wiring, and vacuum diagrams, which makes finding problems like this much easier!
hth!
Joel Adams
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in Forum: C3 Q&A with Dave McLellan
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