(Sorry if this is all over the place. It's been very confusing as to why this won't work.)
Recently picked up a 2003 Yukon XL SLT with the fancy digital dual zone auto control head.
Back story: While initially going through it, found that the water pump was leaking from the weep hole. Replaced the water pump, thermostat (186 deg F), and upper and lower hoses for good measure. One week later, radiator blows out on a hot day (due to possibly sitting with too much water over the winter and freezing). Did a hose flush of the heater cores (forward and reverse) as well as the engine, replaced the radiator, and did a vacuum fill to ensure no air in the system. Replaced the buzzing cab temp sensor above the driver seat as well.
Fast forward and it gets real cold outside, and now I discover there is no heat from front or rear. I found a bad blend door actuator on the rear (did not move when I changed settings) and manually set it to full heat before putting the actuator back in place and unplugging it so it would not move. Still no heat.
I noticed the temp on the mirror was reading in the 90's when it was in the 30's and the mirror would restart at random several times per minute. I replaced the ambient temp sensor in the grill, the temp continued to show in the 90's, but then began reading right after about a half an hour of driving (in town and on highway). Still no heat.
Items replaced:
Water pump
Thermostat
Upper and Lower radiator hoses
Cab temp sensor
Outside ambient temp sensor
Verified no clogs in heater input hose, heater output hose, the hose going to the pipe on the intake, the pipe itself (was clogged but cleaned out). At temp with thermostat open (198-205 as read from the OBD2 port), input hose is hot, output hose is not cold but not as hot as input side.
All actuators appear to cycle when doing the HVAC fuse-pull-relearn (air cycles through defrost/face/floor) and recirc works as the sound increases as expected.
Not sure where to go from here. Is there a way to manually jump the plug for the climate control unit to force it to full heat? Another way to test that I am missing?
(Full disclosure - if there is a way to manually set this thing to full heat for right now, that would be great. I can worry about fixing the rest of it later when money isn't so tight...)
Recently picked up a 2003 Yukon XL SLT with the fancy digital dual zone auto control head.
Back story: While initially going through it, found that the water pump was leaking from the weep hole. Replaced the water pump, thermostat (186 deg F), and upper and lower hoses for good measure. One week later, radiator blows out on a hot day (due to possibly sitting with too much water over the winter and freezing). Did a hose flush of the heater cores (forward and reverse) as well as the engine, replaced the radiator, and did a vacuum fill to ensure no air in the system. Replaced the buzzing cab temp sensor above the driver seat as well.
Fast forward and it gets real cold outside, and now I discover there is no heat from front or rear. I found a bad blend door actuator on the rear (did not move when I changed settings) and manually set it to full heat before putting the actuator back in place and unplugging it so it would not move. Still no heat.
I noticed the temp on the mirror was reading in the 90's when it was in the 30's and the mirror would restart at random several times per minute. I replaced the ambient temp sensor in the grill, the temp continued to show in the 90's, but then began reading right after about a half an hour of driving (in town and on highway). Still no heat.
Items replaced:
Water pump
Thermostat
Upper and Lower radiator hoses
Cab temp sensor
Outside ambient temp sensor
Verified no clogs in heater input hose, heater output hose, the hose going to the pipe on the intake, the pipe itself (was clogged but cleaned out). At temp with thermostat open (198-205 as read from the OBD2 port), input hose is hot, output hose is not cold but not as hot as input side.
All actuators appear to cycle when doing the HVAC fuse-pull-relearn (air cycles through defrost/face/floor) and recirc works as the sound increases as expected.
Not sure where to go from here. Is there a way to manually jump the plug for the climate control unit to force it to full heat? Another way to test that I am missing?
(Full disclosure - if there is a way to manually set this thing to full heat for right now, that would be great. I can worry about fixing the rest of it later when money isn't so tight...)
