Constant Hot air out of vents? Help

[Michael Farrell]

Hi All,

finally got my car up and running but I'm noticing one issue, no matter where my temperature control is "hot" or cold, it blows hot air, Blower motor works on each speed and I can hear the vents open and close when I go from defrost to AC, but toggling between hot and cold I hear nothing which I find suspicious. where should I start for troubleshooting?

 

[L92 OLDS]

1) Do you still have the vacuum operated heater core shut off valve installed? It should be in line with your heater hoses 2) Are your vent doors opening and closing properly?

 

[ck80]

Hi All,

finally got my car up and running but I'm noticing one issue, no matter where my temperature control is "hot" or cold, it blows hot air, Blower motor works on each speed and I can hear the vents open and close when I go from defrost to AC, but toggling between hot and cold I hear nothing which I find suspicious. where should I start for troubleshooting?

I'd start with the air blend door and go from there. Easiest way to check is open the glovebox, empty it out, then press in the metal tab (typically on the driver side of the box assembly) that catches on the dash pad and let's the glove box door drop open all the way dowe towards the carpet.

Look up inside and you will see the cable leading from the climate slider to the pivoting arm that in turn operates the blend door.

 

[jlcustomz]

The heater valve inline on the heater hoses commonly freezes up, also lots of small vacuum hoses & the controller to go wrong & not operate it. You could also clamp a heater hose line to shut it as a test. Valve is cheap & easy but if controller issues are the problem some have put in a hardware store manual ball valve as a temporary or even permanent fix.

 

[axisg]

like others have said, its either in the blend door or the heater control valve. AC cars still flow coolant thru the heater core ( for blend function ) in all settings other than MAX AC from what I understand. Every summer I put the valve on manifold vacuum to keep it closed, then put it back inline for the fall and spring. It's located inline on one of the heater hoses closer to the firewall with a vacuum line from the small vacuum ball mounted to the heater box. When they fail its often in the open position and inexpensive to replace

http://www.rockauto.com/en/catalog/...338,heat+&+air+conditioning,heater+valve,6860

 

[Michael Farrell]

thanks guys, just heading out to take a look now I'll give the above mentioned a try and let everyone know what I find

 

[Michael Farrell]

Hi Guys,
quick update, blend door cable is working from what I can tell, I cant seem to find a vacuum valve everyone mentioned if I follow my heater core lines back to the firewall I find what looks to be an electrically controlled valve running to my blower motor, also noticed my blower motor only functions on high would that affect anything?

 

[Longroof79]

The heater valve is usually positioned on the right side of the intake manifold...at least on a Chevy small block it is. I agree that the problem might be the heater valve, especially if the blend doors are working properly.

 

[Opie Knievel]

If your blower only works on high, there's a good chance that your blower resister is bad or possibly the fan speed switch.

 

[axisg]

http://www.montecarloss.com/community/ubbthreads.php?ubb=showflat&Number=882956

The monte is 95% the same HVAC as the cutlass. This should tell you all you need to know. Note the post with the HVAC top off. To the right next to the red trans dipstick is the heater control valve