No heat on 2001 GMC Jimmy, please help!

[batko_jimmy]

Hello everyone, I have this problem that is really bothering me. My heat does't work. It used to be warm, but not it is as cold as outside of the truck. Before it used to be warm but now it is cold. I checked my hoses, and they all seem to be full with antifreeze. I changed the fluid, radiator cap and thermostat and still no hot. Please let me know if you guys know any other suggestion. Also my panel controler does not seem to work. Please help.

[t01blaze]

Quote: Originally Posted by batko_jimmy

Also my panel controler does not seem to work.

id start with fixing this first...what does not work exactly?

the blower motor comes on, correct? if it only works on high, then the blower motor resistor is likely bad.

more details please

[batko_jimmy]

Actually, yes
I can barely feel anything when it is on 1 2 or 3.
and on 4 it blows cold air from everywhere no matter I set it on feet, panel or window.

[bingedrinker]

its a clogged heater core.they all do it.flushing it out may help but it will need replaced

[epnc]

As binge said, it's a clogged heater core. It also happened to me, no heat whatsoever, another victim of GM's pink antifreeze.

To avoid removing the core as I did: (1) Remove the heater hoses from the inlet and outlet ports of the heater core at the engine compartment firewall. Be careful removing the old hoses as excess force can damage the heater core ports. The smart way is to remove the original hose clamps, slice the now exposed hose ends lengthwise with a knife and then peel radially vs. pulling and twisting. It's a good time to replace the original hoses anyway. (2) Fashion two separate segments of heater hose about two or three feet long at attach to the ports. Dish detergent will help them slide on easily, especially if the rubber is cold. (3) Tie or affix the open ends of these hoses elevated such that they will hold fluid. (4) Purchase and pour in a caustic radiator flush into these hoses and leave overnight. (5) From a hardware store or Home Depot purchase a brass female garden hose adapter to male 3/4'" NPT, 3/4" NPT female-female ball valve, and 3/4" NPT male to male barbed connector, the latter which will connect to output/return flow side of the core via the segment of hose. If memory serves, it was 3/4" hose (vs. 5/8" with the ports being differently sized), but do verify this. It's very important that pressure be applied in the reverse direction of the heater core's normal flow to blow out the deposits. Also, don't forget hose clamps. (6) Attach garden hose, open spigot and bleed air to the ball valve, then tighten garden hose female fitting all the way. (7) Open ball valve. With luck, the deposits will blow out and water will flow through in reverse unobstructedly. Mine did, and I avoided having to disassemble the dashboard and purchase a new core. One year plus later, it still flows and heats fine.

Good luck.

[STXS10]

I did the same as epnc....got me through another winter...but that was 2 years ago. I had to bypass it Nov 2008 due to it finally breaking and leaking

[houston39]

Hi,

This happened to my sister-in-law's Jimmy. I followed the advice above, and flushed out the heater core. Hooked a metal garden hose sprayer into the heater hose and let it run for about a minute.

I was happy when we started it up, and had pretty good heat about 10 minutes later.