Heater control solenoid

[gpd4]

My heater controls do not open and close the door in the system anymore. They were working fine until I had the core replaced (again) a few weeks ago. It was a warrantee deal this time so I took it back to Dobbs and the guy doesn't seem to believe me that it worked when I dropped it off. Long story short...I was told that the part is no longer available - the solenoid, that is. Is he telling me the truth or just being a jacka$$?

 

[Grim-Reaper]

What solonoide? it's all vacume pots. Take the clove box door off. the heater box is directly behind it. the control pot for that is located up there. Knuckle head proably didn't reconnect the vacuum line. If that thing is bad/disconnected then when you switch on the heat your idle will probably come up.
http://www.coloradok5.com/heatercore.shtml

 

[tori89k5]

Start with the beginning.... I just went thru this very problem with mine. First make sure you have vacuum running into the cab. It starts from a line near firewall (not sure where on your '85) then it passes thru the firewall near the AC evaporator (if you have AC) or on the passenger side. If you have vacuum there, pull the glove box out and find where it comes thru the fire wall and trace it as far as you can making sure you still have vacuum there.
Next pull the dash panel off and pull heater control out. You will have a rubber vacuum manifold that plugs into the rear of it. You should have one of those that has vacuum all the time ( when engine is running) Mine was a melted vacuum supply line, so after i fixed that i was good to go.)
If you have vacuum there, move the selector on the heater control and see if it is leaking. If so.... replace it. I believe you can still get this new from GM. If its not leaking, follow the lines to the vacuum actuators that actually open the doors. You can maually compress the diaphrams on them and hold your finger over their port to see if the diaphram is holding or not.
Good luck, TORI