Heater help....
Problem, heater won't shut off. I've tracked it down to the wires for the heater control solenoid. I'm only getting 4-5 volts to the solenoid with the control set all the way cold. Zero volts all the way hot. Solenoid works when I apply 12 volts. Is the dash switch something that I could clean with contact cleaner, or is it a lost cause? Seems pretty pricey to replace.
Thanks in advance. |
RichC10 Welcome to the forum...
Lets get a bit more info to help you out here... What year model are we talking about... When you say heat won't shut off, we talking fan or the heat.. Keep in mind if your blend door is staying open, you will also get heat all the time.. |
[QUOTE=in2pro;242419]RichC10 Welcome to the forum...
Lets get a bit more info to help you out here... QUOTE] Ooops, it's a 99 Suburban. Thanks for the response, I think I have it worked out. The problem was the hot water was not shutting off, always going thru the heater core. The fan and the blend doors work fine. After further searching the web, I found the solenoid is supposed to be getting 12 volts in order to shut off the heater core, so it seems the temp control dial is bad. Rather than spend big bucks on a new heater control, I just rigged a toggle switch to the solenoid. That makes the heat all on or all off, but I can live with that. The truck is only used to tow the boat in the summer, or drive in the winter when it's too cold to ride the bike. |
glad you fixed it.
for others wanting info on this system... there is no heater control valve on a 99 suburban. Coolant is continually flowing through the heater core at all times. the temp blend door is what regulates the heat. the brown wire should have 12volts at the temp blend door actuator but it is not supplied its voltage from the hvac module rather the i/p heater /ac fuse. the black wire is grd and the white wire should have a varying signal depending on the temp control dial position. The voltage change on this wiring is what causes the temp acutator to change the door position. |
Originally Posted by tech2
(Post 242462)
glad you fixed it.
for others wanting info on this system... there is no heater control valve on a 99 suburban. Coolant is continually flowing through the heater core at all times. the temp blend door is what regulates the heat. More Information for FOUR SEASONS 74781 No vacuum, coolant goes thru the heater core, with vacuum the valve closes and the coolant goes back to the engine. I've heard that 99 was an odd model, maybe some didn't have this system, but I haven't had any problem ordering parts. |
ok. i seen these types of valves for rear heat systems, never for the front heater core on 0db2 or newer.
Where is the valve located; by the firewall near the hvac box? |
Originally Posted by tech2
(Post 242494)
ok. i seen these types of valves for rear heat systems, never for the front heater core on 0db2 or newer.
Where is the valve located; by the firewall near the hvac box? |
Was hard to get info but I found some "unclear" pictures on it and it does appear to be going to the front heater core. The valve is stock but can you confirm where all the hoses go.
From what you see...is the valve vacuum controlled and there is a electrical solenoid that controls vacuum to the valve? I assumed the valve would be for the rear system...to close off coolant flow to the rear to provide quicker coolant warm up. |
Originally Posted by tech2
(Post 242553)
From what you see...is the valve vacuum controlled and there is a electrical solenoid that controls vacuum to the valve?
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02 Tahoe heater will not cut off
Just like to know if you got your problem solved? I disconnected the ground at the battery hoping for a computer reset, but no help here. Thanks for any advise.
Terry |
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