When I turn on defrost I get no hot air. Air comes out of the vents nicely, but just not with much heat.

The heater core was replaced a few years ago and I flushed it within the past month or two. The both hoses going to the core were hot enough to burn my hands if I held onto them for more then 4 or 5 seconds. There is no water valve in the lines, the heater core goes directly to the pump and the other hose to the head.

Its about 50-60F outside, so I'm not battling freezing conditions or anything like that.

I occasionally hear a leaf or two go through the squirrel cage but I don't think thats relevant because the air does come out the appropriate vents. Unless the whole core is blocked by leaves.... which I doubt because then I would hear a much bigger racket coming from the box when the fan is on.

Hey, its probably not the thermostat since the hoses are hot. You checked the level of antifreeze?? or it could be an air pocket in the core.

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Mopar 4 Life!!

1972 Plymouth Duster

I have a hole, maybe 1/16" drilled into the thermostat base to bleed air. And eventually, if it was an air pocket it would just get bleed to the top radiator tank, right? I have one of those prestone backflush fittings on the line, so I'll open it up the next time I have it hot to see if any air comes out.

I checked fluid level recently, its above the top of the radiator cores so that couldn't be it.

Check on the top of the heater box for a little metal bar. there is supposed to be a cable attached to it. I would bet the cable going from your heat lever is no longer attached to the metal bar that opens and closes the little door inside the box that allows hot air to get from the heater core to the vents.

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Some units have a damper (or door) for temperature control. It can
be moved by a vacuum or mechanical (cable) setup. If the damper
becomes stuck or the cable slips off the damper can keep all the
heat inside the heater core box.

Hmm, with the stock setup I have its compeltely cable operated. Come to think of it, the "cold -> warm" selecter does have a funny feel to it, perhaps something is busted there. I'll have to check that out.

Another vote for a stuck-open heater door here. Vapor lock in the heater core could also be the problem as already mentioned. However, the radiator is supposed to be the highest point in the cooling system so any trapped air can make it to the radiator. If your front springs are tired or you have the rear end jacked up or front end lowered, the heater core lines may be level or slightly above the top of the radiator (this is the case with my truck) To prevent heater core vapor lock in my truck I always fill the heater core with antifreeze/water before attaching the hoses.

Good luck.

-S/6

PS 50-60* F ?! Thats T-shirt and shorts weather !

Muhaha no thats stay inside bundled up weather. When I was at school in the dorms we had students from Alaska, and when it reached the cold 50-60deg months, to my amazment they were still out in shorts and t-shrits.

Good call on the cables/door guys.

Apparently, whomever installed the heater control and/or box (and no, it wasn't me ) tightend the screws holding the cable down too much, so when the levers were moved the cables didn't move it just kinked itself. Now I need to hunt for new cables. What a pesky design, I'm even pondering replacing it with an electronic control so I can get rid of the cable completely.

A cable I found for my truck that has worked flawlessly for years is an old bicycle hand brake cable. These are plentiful in junkyards...and free

-S/6

I remember a generic choke kit at Kragen. Bicycle brake you say ... I'll have to flip through the phone book and see if theres a bike shop around here.

How long does the cable need to be? I've got 3ft of new bike cable left...

Zorg, thanks for the offer. Turns out the bike store that was in town shut down shop. Went to the local hardware store and they had steel wire. 19awg in 50foot roll was $1.50, which turned out to be a bit small, the 18awg looks to be the original size. Too bad they didn't have it in smaller rolls then 100ft, but for $3.50 I'm not complaining.

The sheith is fine it isn't torn up. So I just have to cut the wire to length and remake the ends, and all is done. I took apart the controls from the dash and only one cable is kinked and needs to be remade. I'll make sure theres plenty of grease in the sheith before I put the wire in this time

I think you can get the bicycle cable at places like K-Mart, Wall Mart or Target. Check in the bike section. A lot of times they have basic repair parts.

I hadn't thought of using a bicycle brake cable. It's a realy good idea.

John

Aren't bike cables made out of stranded cable? How are you supposed to form the looops at the end with that, and I can see them being able to pull the door open but wouldn't the cable collapse when you try to push the door shut?