What are some things to check in the heating system.

The heater is not blowing hot air. I changed water pump and thermostat. Nothing, it seems the water from the thermostat is going through to the radiator.

The two hoses going to the heater blow, right in front of the dash, are warm, but not enough to warm the car.

It's not overheating at idle, don't want to drive the car without checking this.

Any suggestions.

Thanks,

 

Check the posts right below yours. Probably your door actutator.

 

I have had the core get clogged from the new anti freeze that they use . Drained it pulled heater hoses and back flushed refilled with clean green anti freeze and have had heat for several years now. if one hose going to heater core gets hot but other isnt could be your problem too I had the pink red crud build up at cap too.

 

First thank you for the responses. I had look everywhere online, and found this door actuator mention several times. I have to look into this. I have my dad helping me, very old school.

We dumped all the antifreeze to make sure it wasn't clogged and flush with water. He didn't want to put antifreeze just yet, because he didn't want to waste to check.

Right now the radiator has plenty of water, but like I said above, with the thermostat on, water doesn't freely passing back into the radiator. It's almost like the thermostat is shut closed. Without the thermostat it drives but there is no heat, and we haven't gone far.

More research too do.

 

Can you maybe describe this actuator motor and its location. Its on both doors?

Conflicting locations, maybe I'm reading two many postings. One said its behind the dash.

Or behind an access panel under the hood.

What to check for if faulty.

This image is of a on ebay but it said for left door?

 

The actuator i had to replace was located behind the glove box.

My 98 only had one door to control hot or cold. Not sure what you mean by both doors.

One position allowed cold AC air to come in, other position allowed warm heater core air to come in.

Swing the the glove box door down out of the way and i am not sure i actually had to remove the glove box. I seem to remember once the door was swung down there was enough room to get in there. The module is screwed into the plastic housing and will only have an electrical pictail connected to it.

The only way i could remove the screws was to put a 1/4" drive socket - maybe 6mm????- on one of those thumbwheel drives.

Its an assembly similar to the one in the pic but its not that one at all. Pull the assembly out, open it up (think it had screws holding it together) and look to see if the large flat white gear has a crack in it. It wont cost you anything to check and it can be removed, replaced and checked without damaging it.

 

Thanks for that clarification. Will check this out soon. By the way if this door is shut closed, would still be able to feel air coming from the vents?

 

Did you back flush the core itself ? I got my blazer new . I was shocked at the sludge that came out dont know why I try to stay on top of that stuff. Are both hose getting hot going to the core?

 

Yes we did, everything was flushed and both cores get hot.

 

I believe you will still get air movement but that air will not be allowed to pass over the heater core because the door is in the wrong position.

 

Had to work a double tonight, so I just got in. This sounds more and more like the problem, even so with my AC that stopped working this summer. It has freon is there are no leaks and a brand new compressor last summer, but sometime in August it gave out. After spending so much money the year prior, I sort of let it go and figured I messed with it next year.

I'll come back soon, hopefully with some good news.

Thanks again!