Don't say it's the heater core!

So my 97 is not blowing hot air now. Just luke worm air if that. I flushed the system this morning. Let the truck heat up to temp then drained it again. The water that I drains was work but not hot. I tested the thermostat. It opens at around 180 ish. I took the hose and flushed out the heater core, that didn't help either. Any ideas?

 

I've heard the term "burping the system" applied here...?

 

Did that also and it didn't help.

 

I'm guessing you are low on coolant.

Any idea on how much you put in?

Squeeze the radiator hose to push air bubbles out or the system. Leave the cap off and you can see the bubbles .

 

“It’s the heater core!”

 

If the heater core was bad, wouldn't it be leaking and causing water to pool on the passenger side?

 

That's what I thought to. If I turn the heater off when the trucks wormed up and then turn it on it blows hot for about 5 seconds.

 

Could be a small leak just causing vapors to escape. It may or may not be the issue. I just said it because he said not to say it.

Any common signs of a bad core op?

 

did you try turning the A/C off if it was on?
maybe its stuck on the defrost
how many miles do you have?

 

Tryed that also. Truck has about 350,000 and tooend rebuild about 15,000 miles ago.

 

Any one know what a full fill would be? How much coolant? It seems like I'm getting about a gallon and maybe squirt of watter in the system. Also my coolant line into the heater core is hot but not the line out.

 

Sounds like the heater core is clogged. Do you have access to a compressor?

something like this should be able to push blockages out better than just trying to use a hose alone

$85 OTC 6043 Blast-Vac Multipurpose Cleaning Gun

https://www.amazon.com/OTC-6043-Blast-Vac-Multipurpose-Cleaning/dp/B000F5ECRW

 

Heater core could be plugged up with debris.

 

Yeah I do I'm going to blast it with water and air next.

 

Did you check if the blend door is working properly? The heater hose valves and cables?

 

Yeah it's working. I tested that also.

 

So I don't think it's clogged

 

So a little more detail please. Is the air warm all the time or just when fan on high at idle?

I have come to the conclusion that the heater core doesn't have the capacity to throw out HOT air when the ambient temp outside is like 20 degree or below and at idle and in gear (AT at 500 RPM). As soon as RPM's go up to about 1000 RPM it will blow hot. Now it sounds like you've checked the 99% of the typical issues dealing with this - thermostat, air in system, back flushed heater core, etc. The water pump has steel blades and so that's not it unless they are damaged or it's not spinning. The next thing I would do is the CLR flush for 1/2 hour. Only put that stuff in the core and flush out before sealing up the system again. It's a last resort but it does work most of the time if you have a corroded heater core. Be careful using the pressure of a garden hose or compressed air. The core is only designed for 15 psi and you could blow it out of you put more pressure in.

 

When you were flushing the core did you have good flow coming out the opposite pipe/end? If flow was great, could you tell no obstructions in the core? Mmmm

 

Thanks everyone. I got it fixed. Not sure 100% what the issue was but I after flushing the core, changing the thermostat and radiator cap, flushing the radiator and block, burping it and almost 2 gallons of fresh coolant she is blowing hot.