No/very poor front heat

[auh]

I'm not sure what my problem could be. My rear heat blows out much much hotter than my front. If I switch my controls from fresh air to recirculate then my car gets a little warmer, but still not hot.

It's a 93 if that makes a difference.

 

[bajaphile]

I'd check the heater control valve function first since its very easy access. At least on my '97, you can unclip the cable that connects to the valve (right on firewall above engine). Manually rotate the valve to see if it easly moves. If its stuck, that might be your problem.

If not, maybe check your coolant level. Course there will be someone who chimes in with a common issue that has nothing to do with what I wrote.

 

[Wayne]

I'm having the same problem and was told to "burp" the coolant system and make sure it's full of coolant. The factory sevice manual troubleshooting guide says to check the "Heater Relay" located in the driver's kick panel and the "Air Mix Servomotor" located behind the center instrument panel.

I going to do the burp/fill procedure and if that doesn't fix it. I'm betting the Air Mix Servomotor is starting to go south. I have good AC, but only warm air for heat. I can hear the servomotor working when the temp selector is moved from cold to hot and the sound is much stronger going to AC than it is going to heat. My rear heater is also much warmer than the front.

 

[akarilo]

I had to back flush the heater core, all kinds of crap came out of it. It solved the problem.

 

[Wayne]

I had to back flush the heater core, all kinds of crap came out of it. It solved the problem.

When you back flushed the heater core what was your procedure, and did you use any kind of flush or cleaning agent?

 

[capthuff]

Subscribed.... Having the same issue!!

 

[auh]

Does anyone have a good burping procedure?

 

[LTrain]

Check out the first post of this thread: https://forum.ih8mud.com/threads/my-anti-build-named-lucy.810565/

I, too, have the same issue and have done quite a bit of searching on here about it. As stated earlier burping the system, a coolant flush, and the heater core all seem to be commons fixes. The fix in this post was the first I had heard of these parts. I have not had time to address mine yet, but I will be interested to see what your solution is in the end.

 

[Mrtwooooo]

Mine is putting out poor heat as well. I have to put the temp selector all the way to full hot though. Putting the selector in the middle really makes no difference and I've confirmed the valve on the firewall is moving through the entire motion.

 

[kash]

 

[jakesiar]

I just had the same issue w/ little heat. My temp gauge was not going to the 9 OClock position. I replaced my t-stat a few months ago and somehow I did not have the o-ring seated properly on the t-stat. Picked up a new OEM o-ring and all seems well now.

 

[auh]

Update: I might have a lot of air in my system...maybe. I finally figured out a goodish way to burp it. While the engine was hot, I parked the front end on a curb to raised it up, and using rags, I popped the rad cap off. Sure enough I had air on the top of my radiator. Topped it up and recapped it and had really good heat blowing for about 10-15 min. Then it cooled off so I did it again, didn't take as much fluid the second time. Tried doing it again and got a little more air the top of the rad so I topped it with coolant and sure enough, instant heat. But it did start to blow cold again so I did it again, this time no air.

 

[auh]

Did it a third time and got a little more air at the top of the rad. Finally blew cold so I checked one last time and the rad was fill so I called it quits and I'll check again tomorrow.

 

[Mixelplix]

It's unreasonable to assume there would be air left in the system after a few hundred miles, right? Mine's been like this for two years - and I'm leaning toward the module / amplifier issue referenced in the other thread above.

 

[leonard_nemoy]

I had similar issues with mine. I fixed it by flushing the heater core. What gave the heater core away as the culprit was the fact that I would have good heat driving up the mountains with constant high rpm's which would put more pressure on the cooling system forcing the coolant through my clogged heater core. Coming down the mountain primarily costing the heat would go away. Flushed the heater core with a hose garden followed by 30 psi of shop air and a bunch of crud came out. Now it is fixed.

 

[auh]

I would have flushed it, but could only find one side. Does someone have a picture that shows where both hoses are?

 

[Wayne]

I bought the Lisle Spill Proof Funnel off Amazon for $34 and performed a burp fill process. http://www.amazon.com/gp/product/B001A4EAV0/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 Very few air bubbles surfaced.

The next two things I'm going to do is back flush the heater core and check the Air Mix Servomotor for full function. The heater core is the original and it has never been flushed, so that's a definate maybe as the problem or part of the problem. I can hear the servomotor operating behind the selector panel and it sounds strong going to cold, but weak and jerky going to hot. I'll post my findings.

 

[auh]

I had to drive my truck around until it got hot, then park it with the front end on a curb before I saw ANY air. The bump of getting on the curb I think helped move the air to the front. I left it running the whole time and used a few rags to open the cap so I wouldn't get burned. Did it 4 times and added a few cups of coolant each time. Over all I added almost a gallon by the last time I did it

 

[Aggiesdm]

I had similar issues with mine. I fixed it by flushing the heater core. What gave the heater core away as the culprit was the fact that I would have good heat driving up the mountains with constant high rpm's which would put more pressure on the cooling system forcing the coolant through my clogged heater core. Coming down the mountain primarily costing the heat would go away. Flushed the heater core with a hose garden followed by 30 psi of shop air and a bunch of crud came out. Now it is fixed.

Leonard, can you give a few details of how you flushed it? Did you just use the in/out lines at the firewall? If so, how did you get the water hose onto the heater hose? Did you just hold it up close or did you get a coupling? Thanks

 

[leonard_nemoy]

I just held it up to the hose, then I stuck a blower nozzle into the heater hose and clamped it down with a hose clamp. I disconnected the hoses as far from the firewall as I could so I had some heater hose to work with.