Poor Heat, Not Sure Where to Start

[GbByChubsy]

Well, I have poor hear and air flow from the both rear and front vents. Not blowing hard enough and not nearly warm enough. Blower motor still runs but I believe is starting to die, still more air flow should be coming regardless.

Not sure where to start, don't want to rip off the dash for no reason. Need some diagnostic help/steps

[Graplr]

If the blower motors aren't working, I'd start by pulling them and/or applying 12 volts directly to see how they run.

How is your engine temperature? How long does it take to warm up (the engine)?

[PrivatePilot]

Poor airflow is usually a result of one of the flapper / distribution flaps not working properly within the HVAC box. Unfortunately, it's behind the dash and can be a miserable thing to work on.

Do you have more air flow in some positions (dash vents, floor, defrost) vs others, or is it a universally bad flow across all of them?

Can you hear the blower motor speed and up and slow down when you change positions on the control? Does it appear to be working at full speed on the "High" setting?

And as Graplr asks, what is your engine temperature getting up to? Lack of heat is often a result of a thermostat that is stuck open, so the engine never actually heats up properly.

[57diesel]

Pilot asks good questions as far as does the air move to the various vents when you turn the dial. That era was terrible for the quality of all the components related to the duct work. The motors fail which depending on which one may not be too bad to replace. The air doors in the ducts also fail and the doors are an extra pain to work on. On both my 96 and 97 the mode doors were messed up. Its a set of 3 that run off one motor. One of them falls off its pivot and jams up the rest so you pretty much get no air out the left side vents and it does not really change much, it just blows out most of the vents most of the time. I did a write up on the repairs to my 96 in the interior section.

As far as the hotness of the heat goes I had a flush done on mine last week and it really helped. Mine would only blow hot when going down the freeway. Around the city and at idle it was barely warm. Don't know if its a factor or not but mine still had dexcool in it.

[tookielee]

Also, the fins get clogged, and won't let air flow thru, may need to wash them too.

[JMJNet]

T-stat?

[PrivatePilot]

Originally Posted by tookielee

Also, the fins get clogged, and won't let air flow thru, may need to wash them too.

That was on my mind, hence my question about airflow being consistently poor across all settings, or just one.

I had this happen on an old car of mine - the AC evaporator leaked and the oil collected garbage to the point where no air could get through.

[GbByChubsy]

Air flow does changes properly based on the controls of high down to low. The temp is fine, around 185-190 consistently.

Also as someone noted above, I have poor heat at idle. When I am at a traffic light, the flow seems to reduce a bit, and it does not blow hot. At normal speeds it is fine, but at stops it does this.

More over, air flow is consistent at all selections, floor, defrost ect.

[Graplr]

Originally Posted by GbByChubsy

Air flow does changes properly based on the controls of high down to low. The temp is fine, around 185-190 consistently.

Also as someone noted above, I have poor heat at idle. When I am at a traffic light, the flow seems to reduce a bit, and it does not blow hot. At normal speeds it is fine, but at stops it does this.

More over, air flow is consistent at all selections, floor, defrost ect.

That does sound like either a blower/voltage issue or a block in the heater core fins.

A few weeks ago someone was posting about the same issue as yours. That is poor heat around town or at idle but okay on the highway. He did a coolant flush and he stated that solved his issue.

[57diesel]

My temp gauge always held steady. My theory was that there was enough internal clogging in the heater cores that you needed the water pump to be spinning a bit faster to get the pressure to circulate well through the cores. At highway speeds I think the heat was hotter before the flush but after the flush its about the same once the temp gauge comes up regardless of speed.

I had a shop flush mine since its been single digits F around here and I have no inside space to to work. Another member recently had the same issue (maybe his never got hot) and he back flushed his core himself with a garden hose.