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I need to replace a badly leaking heater core on a ...
Sent to Car Experts October 10 12:49 PM

I need to replace a badly leaking heater core on a 1999 S10 Blazer LS. What is the best method to do this? How much do I really need to remove to gain access to the core? Are there any "shortcuts" for this job? It looks like a monster job so far. Thanks, Jim

 

Optional Information:
1999 Chevrolet S10 Blazer 4.3L F.I.

Already Tried:
Bypass the heater

Customer (name blocked for privacy)
Status:  Closed   Value: $8
Info Request
October 10 1:03 PM (13 minutes and 47 seconds later)
         
REPLIED to Info RequestCheck Mark

Hi Jim,

You are correct, this is a hard one. The whole dash assembly has to be removed and then the heater box is held by nuts on the motor side of the firewall. It also must have the right front inner fender panel removed to gain access to some of the retaining nuts, as well as the blower motor resistor, because it has a nut hidden behind it. The heater case has to come out as a complete unit and then you can split the case to get the core out. If you are sure you want to attempt this job drop me a note and I will try to help. It is an all day cookie and there really are no short cuts.

Bob

Picture
Bob -- Auto Service Technician -- 99% Positive Feedback on 1111 Car Accepts
40 year GM Tech. +30 Certified. ASE Master Tech.(expired, retired) Medium Duty, Heavy Line, Retired
Reply
October 10 2:14 PM (1 hour and 10 minutes and 57 seconds later)
         
Reply to Bob's Post: Hey Bob,
Thanks for the reply, even though it was not what I wanted to hear. It will be a long, cold winter without any heat, so I guess I'll give it a shot.I'm guessing I'll also have to break the A/C refrigerant lines, but I'm more worried about the airbags and steering column. I'm listening to anything you have to suggest.If you have any specific questions of me, just ask.

Thanks, Jim
Customer (name blocked for privacy)
Answer
October 10 2:22 PM (7 minutes and 58 seconds later)
         
REPLIEDCheck Mark

First start of by unhooking the battery. I think you can just lower the steering column without having to mess with the airbag. You may not have to blow the AC system either. It is pretty much just a matter of getting the dash pad and related items out of the way. I have been know to just take everything loose and pulling the dash pad rearward and then blocking the right side of it up with a 4X4 just to get enough room to access the heater box. The other hard part is getting the nuts off on the firewall side. Sometimes you can just drop the inner fender panel and pull it back far enough to access the 10mm nuts that hold it in place. There is one nut hidden under the blower motor resistor. Note all the electrical connections and when the case is put, you can split it and remove the core. I will be here for a bit if you need me. Good luck.

Bob

Picture
Bob -- Auto Service Technician -- 99% Positive Feedback on 1111 Car Accepts
40 year GM Tech. +30 Certified. ASE Master Tech.(expired, retired) Medium Duty, Heavy Line, Retired
Reply
October 10 3:33 PM (1 hour and 11 minutes and 1 second later)
         
Reply to Bob's Post: Bob, I'm not sure what you mean by the "inner fender panel". Will that be obvious when looking under the hood? By the way, some time ago, the actuator that diverts hot air to the floor broke and I now only get air thru the dash vents. Will this be something I can get to with the heat box removed ?
Customer (name blocked for privacy)
Answer
October 10 5:43 PM (2 hours and 9 minutes and 19 seconds later)
         
ACCEPTEDCheck Mark

Hi Jim,

Sorry to take so long getting back to you. Had to run downtown. The inner fender panel is the part that sets behind the right front wheel between the wheel and the motor and covers the motor area from the wheel and the road. Really big, think on yours it is plastic. Lots of stuff mounted on top of it under the hood. ECM, modules etc. It is in the way of you getting to the nuts on that side that hold the heater case through the firewall. You will find that the most outside nut will require an end wrench to remove as it is really close to the right side exhaust manifold. Most of the others can be taken off with a 1/4 inch drive ratchet, etc.

As for the actuator door, it is located more in the center of the case behind and below the radio. You may get lucky and find the problem when the case assembly is out and apart, but if memory serves, the door inside the case is the hot and cold air mix door. They do have some problems with the actuator that works the mode door ( defrost, heater outlet, etc.) So, check that out while you are there.

 

Hope this helps. Will be back and forth on the PC this afternoon and evening if you need me. An accept and positive feedbac are always appreciated.

Bob

Picture
Bob -- Auto Service Technician -- 99% Positive Feedback on 1111 Car Accepts
40 year GM Tech. +30 Certified. ASE Master Tech.(expired, retired) Medium Duty, Heavy Line, Retired
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