The rear heat blows cold air. Yesterday morning it felt like the a/c was on in the back. At lunch time I got in the back seat and turned it on from the back and adjusted the temp and it blew kind of warm. This morning it was freezing cold again. Even after letting the car warm up. Front heat works great. Any ideas?
Rear heat not working ? The blower motor isn't working ? No air coming from the rear vent's ? Is it just a yukon or XL or denali ? What size engine ? 4.8 , 5.3 or 6.0 l Manual or automatic climate control ? Does the blower motor work on any speed ? The front an rear heater system are seperate , have there own electrical circuits . Could have a couple of different systems ,could have a control processor or relay's an a resistor block . Do you know how to test automotive electrical circuit's using a wiring diagram and a DVOM - digital volt ohm meter ? Plus to get at the rear heater-A/C unit you would need to take the right rear trim panel off .
2003 Tahoe No Rear Heat Fix Suburban Yukon XL Repair
SOURCE: Yukon A/C, rear blows cold, front ducts a LOT warmer.
There is only one A/C system split into 2 zones. Check the blend door actuator, it may have failed in one position or something may be jamming it. Also check the control panel in the dash, My 98 yukon did the same thing, no matter what temp you selected for the front it would blow at about 70 degrees. There is a circuit board in the control panel that gets corroded and one of the circuits controls blend door operations. Have a look.
SOURCE: 2002 GMC Yukon blows cold air from the front, rear works fine
check you antifreeze level and make sure its full
SOURCE: 2005 Yukon Denalli - Blow cold air out the drivers side
the passenger side electronic controller is sensing the passenger side temperature is cooler than it really is, which causes the controller to increase the hot water flow to warm up the passenger area...any time you replace a battery or loose your charge, the HVAC module will need to be reset...Try this...
Remove your hvac fuse for 10 sec - reinstall fuse.
Start engine "DO NOT TOUCH ANYTHING FOR 3 MINUTES"
Recalibration of module will accure when power is lost (fuse pulled, battery changed or died)
If hvac reset did not work you have a trouble code - reset BCM
There are two ways to reset your body control module
Go to the GENERAL
Remove BOTH battery cables (for the sake of CAUTION remove air bag fuse and wait 5 MINUTES)
Hold both cables together for 1 minute - drains KAM (keep alive memory).
Put everything back together
Start the engine "DO NOT TOUCH ANYTHING FOR 3 MINUTES"
If you have no broken parts - system not default (normal operation)
If that works it just saved you 600 dollars...dealer costs to repair.
Good Luck...please rate me a fixya.
SOURCE: Air Conditioner Problem
the most common problem here is a defective air temperature control blend door actuator, this is what moves the door that controls air flow across the heater core or the ac evaporator core, to replace this requires u remove the dash assembly.
Testimonial: "good"
SOURCE: 2002 GMC Yukon front A/C blowing warm air
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