After doing many searches...i am a bit confused on what the problem might be.....AC works fine in the front and rear....but when heat is on....the roof vents in the back seat...and far rear (ext model)...blow cold air....floor vents in the same places...do the same thing....If i leave it running ALONG time...it will get luke warm...but barely.....Best i can figure from other posts...is that its the temp control valve....would this be right...or is it something else...actuators seem to be working now...but am going to replace as they were clicking a little when it was really cold out...but seem to be working now.....or could it be the actuator...thanks for any help....this is a 2004 Trailblazer...EXT/LT
no HEAT from roof vents?
- Thread starter convincer253
- Start date
Could be the temp actuator, or it could be a lack of hot coolant flow to the rear heater core. Go underneath the rear passenger side and find the AC and heater hoses, and see if you can feel any heat on the hoses that should be hot after the engine is warmed up. Could be a clogged heater core, obstructed hoses (it's a LONG run) or a valve issue up on the firewall.
GM had so many complaints about low heater performance on EXT/XL vehicles that they added an electric flow booster pump in later model years, and it's available as a retrofit kit (not free). I don't have one, so I never really kept on on the details of when it was offered.
GM had so many complaints about low heater performance on EXT/XL vehicles that they added an electric flow booster pump in later model years, and it's available as a retrofit kit (not free). I don't have one, so I never really kept on on the details of when it was offered.
If you just bought the vehicle after last winter this will be learning experience for you.
It takes a long time if you turn the rear heat on from a cold start. The engine will have a hard time heating up as well. What I usually do is wait until the engine is fully warmed up and then turn the rear fan on. It only takes a few minutes for hot air to start blowing then.
It takes a long time if you turn the rear heat on from a cold start. The engine will have a hard time heating up as well. What I usually do is wait until the engine is fully warmed up and then turn the rear fan on. It only takes a few minutes for hot air to start blowing then.
Thats the way i do it..but after its warmed up and i turn the rear on..it still only blows cold air from the roof vents...Will check hoses and see how they feel and go from there...thanks all...
convincer253 said:
I think that small vacuum hose on the side of the intake resonator goes to the valve to allow coolant to the rear heater core. I believe its electrically switched.
If the rear heater core was blocked then the lines would stay cold regardless. So that's not so intuitive to check.
Got my vehicle in the shop today and checked a few things out....If the long lines that eveyone is talking about that go to the rear....are the long aluminum lines that run along the frame on the passenger side.....they were cold....not even warm....but this is with the rear heat off...Let engine warm up completely to 210..straight up and down on the gauge....then turned the rear heat on...and it started to get warm after about 20 minutes....it was blowing warm air....not hot...but it was warm.....So it does appear to be working ....Is there any way to get it to heat up faster....someone mentioned a pump in line or something like that...would this help.....so maybe someone can help with these questions:::
Where do i get this pump and anyone have the part # ?
Where is this pump installed and mounted?
Is it a big job to install...any pics or posts about installing?
Where is the rear heater core located and how big of a job is it to clean it..if it is plugged or partially plugged
Dont know if it matters....but when it was working yesterday...it wasnt as cold as it has been...it was in the mid 20's.....when it wasnt working it was in the low teens
Where do i get this pump and anyone have the part # ?
Where is this pump installed and mounted?
Is it a big job to install...any pics or posts about installing?
Where is the rear heater core located and how big of a job is it to clean it..if it is plugged or partially plugged
Dont know if it matters....but when it was working yesterday...it wasnt as cold as it has been...it was in the mid 20's.....when it wasnt working it was in the low teens
Pump:
TSB 05-01-37-002, May 2005
Poor Rear Heat Performance (Install Auxiliary Heater Pump)
2003-2005 TrailBlazer EXT
Condition: Some customers may complain of poor 2nd and/or 3rd row seating heater performance when the vehicle is at idle.
Cause: This condition may be due to lack of coolant circulation to the rear heater core.
Correction: Install auxiliary heater pump package. (P/N 89024885 L6, 89024886, V8) This pump will improve coolant flow to the rear heater core.
The other hardware is all under the rear interior panel on the passenger side of the way back. Heater core is item #16. As usual, everything is built around it.
TSB 05-01-37-002, May 2005
Poor Rear Heat Performance (Install Auxiliary Heater Pump)
2003-2005 TrailBlazer EXT
Condition: Some customers may complain of poor 2nd and/or 3rd row seating heater performance when the vehicle is at idle.
Cause: This condition may be due to lack of coolant circulation to the rear heater core.
Correction: Install auxiliary heater pump package. (P/N 89024885 L6, 89024886, V8) This pump will improve coolant flow to the rear heater core.
The other hardware is all under the rear interior panel on the passenger side of the way back. Heater core is item #16. As usual, everything is built around it.
Going from memory - but I believe that the roof vents are A/C only. Heat only blows from the floor vents. Also the floor vents only work with a certain setting on the front vents (it may be that the air needs to blow from the floor vents at front). This always seemed to me to be poor design. I think it's described in the manual.
You should see from the plenum design that whatever temp airflow could go low is the same that can be flapped high.
I paid someone to replace my rear heater core....grrr....now i have not heat in the back seat (so the same issue) and the A/C no longer gets cold. What do I check? Im not sure if they are the same or multiple issues but I know it all started after that guy "fixed" it for me
The guy told me that I needed a evaporator repair kit and someone else suggested that i have the a/c recharged. I think I should just go get a new car all together but I wont so im going to have to fix this.
The guy told me that I needed a evaporator repair kit and someone else suggested that i have the a/c recharged. I think I should just go get a new car all together but I wont so im going to have to fix this.
apage923 said:
So whoever replaced your rear heater core didn't really replace it or never bothered to check to see if your original complaint was dealt with?
You deserve to get your money back UNTIL the problem is fixed. How do you know they actually did anything if it wasn't fixed?
Was the heater core being replaced a diagnosis that they made and noted it on the quote? If so then you definitely should get your money back. Sounds like your getting shafted here.
Well it started off with a small drip from the back passenger side, the drip steadly got bigger over the course of a few months. I looked into it and decided it was the rear heater core. I usually handle issues myself because I hate to pay someone when there is so many resources that can help me get through any project. BUT, I was talking to my step dad and he insisted on helping me out and called this guy because I was to busy to get into it. So the guy did stop that leak, but then the day after I picked it up the air stopped working. I took it back to him and he had it for a few days and said he couldnt get it to stay charged and told me he was told it need an evaporator core repair kit. He also said he was trying to find one. Anyway he never did...Im sure he didnt try. So I go on about my busy life waiting, then it gets cold out and thats when I found out the rear heat was jacked up. 
I found the kit online for about $200, but then, I got to alking to the guys at work and they are telling me to just try to recharge it and said try a a leak check, because if the evaporator core is bad then there would be an obviouse leak, which there never has been.
So I have no desire to take it back to that guy, and really dont want to put my step dad in the middle of anything, so im eating that loss, and just need to know where to start.
Would anyone agree to try the recharge kit as a first, less expensive, step????
I found the kit online for about $200, but then, I got to alking to the guys at work and they are telling me to just try to recharge it and said try a a leak check, because if the evaporator core is bad then there would be an obviouse leak, which there never has been.
So I have no desire to take it back to that guy, and really dont want to put my step dad in the middle of anything, so im eating that loss, and just need to know where to start.
Would anyone agree to try the recharge kit as a first, less expensive, step????