My heat sucks

[/6 Matt]

So, my heat epically sucks.

The begining of this winter I noticed my heater was blowing ice cold air. So after screwing with that stupid valve on the passenger side inner fender and eventually got it so that the air blowing out was this luke warm room temperature bs. So for the hell of it, I bypassed it. Then I achieved soft heat.

So I said, let's flush the cooling sytem, maybe that's it.

So I got some antifreeze and flushed the whole system and used the heat on the way to and from work. No change.

So I was looking at my heater hoses and thought, gee, let's route the hoses over the cylinder head right where the intake and exhaust mate to the head, let's pickup some extra heat. So tonight on the way from work, the heat was doing well... Kinda. It was blowing out warm, but the car itself wasn't that warm. The inside was like a whole 5 degrees warmer than outside, but I was still cold. The water flows fine to and from the heater core, it was the first thing I flushed and I verified that water was flowing just fine through the hoses. The hoses were hot.

I don't get it. I have a 195 thermostat and I know for a fact that its working right, as per the hot water coming in the radiator. What's wrong?

 

[gdrill]

Possibly the door in the heater box that determines hot or cold air flow is not moving with your slide control. Are the heater hoses themselves hot?

 

[rigrunner]

my valiant does this every winter. i back flush the heater core and good to go till next winter. good luck.

 

[/6 Matt]

Possibly the door in the heater box that determines hot or cold air flow is not moving with your slide control. Are the heater hoses themselves hot?

The door doesn't move at all, It's been rubberbanded shut every winter since we bought the car. And as for the heater hoses, yes, they were hot before and after I relocated them.

my valiant does this every winter. i back flush the heater core and good to go till next winter. good luck.

The heater core was the first thing I flushed before I focused on the rest of the cooling system.

 

[younggun2.0]

it can only be two things.....

1. there is no/not enough coolant flow thru the heater core. think of it as a mini radiator. with engine running and engine at temp both hoses should be warm/hot to the touch. squeeze the outlet house coming from the fire wall. you should feel coolant flowing thru. it its slow flowing or not at all you can disconnect both hoses from engine and flush the core itself with the garden hose. it should flow freely. if no flow or very little flow then its time to replace it.

2. the flapper in the heater box is not in the correct location. it either pulls air from the cowl vent directly into the passenger compartment or it pulls the air thru the heater core into the passenger compartment. that is what heats the air. you can look under the dash and follow the cables from heater controls to the flaps on the heater box. alot of times the ends break off.

 

[/6 Matt]

1. There's plenty of flow to and from the heater core, as confirmed when I flushed my cooling system.

2. If the flapper valve you're talking about is right above the transmission tunnel, then it's rubber banded closed.

 

[OwdKasd]

How bout the heater control valve? I'm not positive but You should a Vacuum activated valve that controls the Water flow to/Through the Heater Core. Might be cable activated. Can't remember exactly. I once bypassed it with a deep socket and 2 hose clamps and got perfect heat.

 

[Johnny Dart]

How old is your heater core ?
This is usually the first indication of a bad heater core.

 

[67Dart273]

You can eliminate everything except "stuff in the heater box." If t he car is running at normal temperature, and both hoses are HOT, then the problem is NOT coolant flow.

It's a blower/ air door problem

You have a shop manual, Matt? You talking about your 70?

There's a free 70 manual posted over at MyMopar. You have to play with the page numbers though, as they don't follow the "dash" Mopar numbering:

http://www.mymopar.com/index.php?pid=31

The linkey

http://www.mymopar.com/downloads/servicemanuals/1970_Plymouth_Service_Manual.zip

 

[/6 Matt]

How bout the heater control valve? I'm not positive but You should a Vacuum activated valve that controls the Water flow to the Heater Core.

I bypassed it and then later ripped it out if the car because it was a useless piece of junk that I've neen fighting with since dad gave me the car. Down here was where I talked about that, but I didn't describe the situation very well because I forgot what the valve was called. My bad...

And the car is the one in my signature, I forgot to specify. My bad, again.

So after screwing with that stupid valve on the passenger side inner fender and eventually got it so that the air blowing out was this luke warm room temperature bs. So for the hell of it, I bypassed it. Then I achieved soft heat.

 

[/6 Matt]

How old is your heater core ?
This is usually the first indication of a bad heater core.

That's what I was thinking myself, but I'm not sure if I'm up for that project.

You can eliminate everything except "stuff in the heater box." If t he car is running at normal temperature, and both hoses are HOT, then the problem is NOT coolant flow.

It's a blower/ air door problem

You have a shop manual, Matt? You talking about your 70?

There's a free 70 manual posted over at MyMopar. You have to play with the page numbers though, as they don't follow the "dash" Mopar numbering:

http://www.mymopar.com/index.php?pid=31

The linkey

http://www.mymopar.com/downloads/servicemanuals/1970_Plymouth_Service_Manual.zip

That's more along the lines of what I was hoping, maybe. I do have a 1975 Factory service manual that I got from my auto teacher when he retired, but I didn't have a 70 manual till now. Thank you so much for that awesomely valuable link!!! :cheers:

 

[OwdKasd]

I bypassed it and then later ripped it out if the car because it was a useless piece of junk that I've neen fighting with since dad gave me the car. Down here was where I talked about that, but I didn't describe the situation very well because I forgot what the valve was called. My bad...

And the car is the one in my signature, I forgot to specify. My bad, again.

Okay, I got ya' I gotta agree with 67dart273 then. I thought you had modded the cold air blend door already. You're on the right track now.:glasses7:

 

[RedFish]

water temp an flow is only half of a heat exchagers function. Air flow through it is the other half. I'll guess the air comming out of the vents is passing though only a few square inches of the exchangers total area. The majority of it is blocked with dust, leaves, etc

 

[65-440]

Just because your hoses are hot doesn't mean the water pump is working 100 %. Have you removed the inlet hose to the heater core with the engine running? .. Your hoses can still be hot with half the flow ...

 

[wjajr]

Determine if coolant is reaching thermostat’s rated temperature, if not, remove and test stat in a pan of hot water; replace as necessary.

At the heater core’s end of the system:
Several conditions will cause poor cabin heat the first you have addressed by flushing the unit for good flow. This leaves the heater box with “rubber banded door” which is not necessary with a properly functioning box.

Two reasons for poor heat production come to mind; air flow through heater core is blocked by assorted trash such as leaves and rodent nests etc., and or air control flaps have lost their ability to seal off incoming cold air that mixes with heated air destined to cabin and defroster.

You need to remove the heater box, clean it out, and rebuild it with new seals & gaskets. Unfortunately Detroit Muscle does not offer rebuild kits for trucks, but that shouldn’t stop you from adapting some thin foam cut to replace the old decomposing foam on internal flaps.

 

[jomoper]

water temp an flow is only half of a heat exchagers function. Air flow through it is the other half. I'll guess the air comming out of the vents is passing though only a few square inches of the exchangers total area. The majority of it is blocked with dust, leaves, etc

X2
Was thinking the same thing . My heater housing was crammed with leaves and crap when I removed it .

 

[kt340sport]

Is the system pressurizing , i would pressure test the rad cap too.

 

[superchargeddrt]

So I know it sounds stupid and I hate to admit it, but in the 80's I had a 74 Dart Sport that I couldn't get any heat out of. I suffered almost the entire winter scraping the ice off of the INSIDE of the windshield. I tried flushing the system and blocking part of the radiator but still couldn't get any real heat. Then while working on my radio under the dash I found it. The cable from the temperature adjustment had come loose. I put it back on and wa La Heat!!!! Just something I would check.

 

[1wild&crazyguy]

its gotta be the lil door, door seal.
Does it get warm at idle parked and cold when u drive it?

 

[67Dart273]

Just because your hoses are hot doesn't mean the water pump is working 100 %. Have you removed the inlet hose to the heater core with the engine running? .. Your hoses can still be hot with half the flow ...

When both hoses are hot you should be getting plenty of flow. Temperature drop across a heat exchanger for both sides tells the story. Those hoses on an engine at normal temp should be so hot you cannot put your hand on 'em for long. If both hoses are substantially hotter than the air output, then it's not water flow as a problem.

 

[65-440]

When both hoses are hot you should be getting plenty of flow. Temperature drop across a heat exchanger for both sides tells the story. Those hoses on an engine at normal temp should be so hot you cannot put your hand on 'em for long. If both hoses are substantially hotter than the air output, then it's not water flow as a problem.

i know what you are saying, and it sounds good in theory .. i dont want to come off as a jerk, but i do this everyday and is my career. i said this comment out of personal experience, matter of fact i just worked on a truck that had no warm airflow from vents. both hoses at the core were hot as hell, removed inlet hose and found hot coolant just sitting there. removed water pump and found the impeller freespinning on the shaft ... vehicle never overheated ! there goes your no flow but hot hoses ... heat will transfer through fluid ....

 

[Bulldozer]

my heater kicks ***

 

[plum crazy dart]

^^^^^ lol

 

[67Dart273]

i know what you are saying, and it sounds good in theory .. i dont want to come off as a jerk, but i do this everyday and is my career. i said this comment out of personal experience, matter of fact i just worked on a truck that had no warm airflow from vents. both hoses at the core were hot as hell, removed inlet hose and found hot coolant just sitting there. removed water pump and found the impeller freespinning on the shaft ... vehicle never overheated ! there goes your no flow but hot hoses ... heat will transfer through fluid ....

That's real funny, because the three vehicles I've found (in my lifetime) with rusted/ busted pump impellers were not producing any heat in the heater AND the hoses were not getting hot. "Warm" maybe.

You must have the magic truck, because what you describe goes against all theory of heat exchangers. For the record, I worked in the HVAC industry for about 12 years, and liquid -- to liquid and liquid - to air heat exchangers were 'part of the deal.'

Is it possible that the hoses were heating up from the exhaust manifold radiated heat?

 

[65-440]

That's real funny, because the three vehicles I've found (in my lifetime) with rusted/ busted pump impellers were not producing any heat in the heater AND the hoses were not getting hot. "Warm" maybe.

You must have the magic truck, because what you describe goes against all theory of heat exchangers. For the record, I worked in the HVAC industry for about 12 years, and liquid -- to liquid and liquid - to air heat exchangers were 'part of the deal.'

Is it possible that the hoses were heating up from the exhaust manifold radiated heat?

Not likely, trust me this truck blew my mind. And most veteran people in the shop too ! ... Was on a late '90s navigator .. Don't know how both heater hoses were hot, but believe me they were, and even with the inop water pump the vehicle operating temp never spiked up.