My heater sucks!

[AirSpeed]

I recently bought a 72 GMC 4X4 and I cant get any heat out of the heater. the fan blows fine, the defrost/heat lever works fine, the temp lever works fine, water is flowing through the heater core, everything seems to be in order except I get lukewarm air only. My 69 puts out so much heat I have to roll down the windows, I cant figure out why I am getting no heat out of my 72. I have read other threads concerning heater problems and none of them seem to be the answer. Anyone have any ideas? Thanks!

[knsmodels]

my 72 blows hot once it is warm the only time it doesnt is if the coolant level gets low....

[mikajo39]

Hmm that is funky, coolant level? Do a radiator flush? Because my heater blows hot enough to cook weenies on it

[dwcsr]

I just replace my core and blower motor today. It was packed with leaves and dirt. once I cleaned out all the junk the blower was actually ok. Make sure the doors are working when you move the levers. Also make sure that the hoses are not clogged and restricting water flow.

As a note if you replace the core don't use a core from mexico. Its a PIA to get the brackets to go under the pipes. Advance Auto Parts sells the Mexico cores under the Ready-Aire brand.

[unclewatts]

Sounds like you might have a thermostat that is either frozen open or missing. You might check that.

[stevewhitmore]

Second that on the heater core brackets, but I got my heater core from LMC and had the same problem with the brackets, had to force them into place and praying that I didn't damage the core pipes.

[extd56]

It sounds like the thermostat is missing, check to make sure that both of the heater hoses are hot once the motor warms up.

[gcsupraman]

Originally Posted by AirSpeed

I recently bought a 72 GMC 4X4 and I cant get any heat out of the heater. the fan blows fine, the defrost/heat lever works fine, the temp lever works fine, water is flowing through the heater core, everything seems to be in order except I get lukewarm air only. My 69 puts out so much heat I have to roll down the windows, I cant figure out why I am getting no heat out of my 72. I have read other threads concerning heater problems and none of them seem to be the answer. Anyone have any ideas? Thanks!

Where is your temp gauge at? Is it reading somewhere in the middle?

I installed a 180 degree thermostat and that killed the hot air - now it's just warm. Just curious if your truck is not warming up (themostat issue) or your truck is showing fully warm and there is another issue.

-Greg

[Sport/Truck]

Every thing mentioned above should get you going.

If you take your core off you can have it tested at a local radiator shop.
Mine is original and the radiator shop said as nice as it was my truck must be real nice.
I had spent lots of time getting little seeds out of the fins on the core. Just use compressed air and taped it until I thought i had it be best I could do.
I powder coated the hangers just so they would never rust.

Also get some foam to put around the heater core outlets to keep dirt & cold air from getting in. I see allot of people leave them off. A new firewall gasket from Classic Heartbeat will Finish the job. Be sure you use new butyl tape between the core and the box, just like factory!
If you really want it to look nice a bit of Gibbs oil will make the dry fiberglass

look new. And no, it does not collect dirt.
s/t

[Sport/Truck]

I guess with out a before picture it hard to tell what the improvement was.
So here it is.