Non-mopar tech question, sorry...

-
65LoveAffair

65LoveAffair

Whovian
Joined
Aug 24, 2010
Messages
2,300
Reaction score
283
Location
Decatur, IL
I posted this on the fortrucksonly.com site yesterday, but haven't gotten any responses. I know the member traffic here is larger, so I figured I'd post it here too.

My 92 Ranger, Sam, doesn't have any heat in her at all. I swapped the thermostat because I already had one, and I have some heat now, but it is intermittent. It will get warm while the truck sits and idles, but as soon as I start driving the heat cools off. Does this sound like a heater core issue? Ford heat is notorious for melting you out of the truck pretty quick, but Sam takes forever to put out even the little heat that she does. I'm leaning toward the heater core, but it's not leaking, the windshield isn't fogging up, and I don't smell antifreeze. Of course, those symptoms all point toward a leaking heater core and not one that's just gunked up inside. I would appreciate any and all suggestions. Thanks in advance!
 
Sounds like a vacuum issue. Look under the hood over by the heater control valve is. Look at the vacuum line going into the valve. They are bad about rotting and even sometimes falling onto the exhaust manifold.

Also look at every other vacuum line you can find. Something is either rotted and leaking or disconnected and leaking, causing the blend doors to move from lost vacuum when you accelerate.
 
Check the input and output hoses are both getting hot ?
 
69FBCuda said:
Check the input and output hoses are both getting hot ?
Click to expand...

X2
An easy way to tell if you have a flow problem.
If one hose is good and warm and the other is cold, then disconnect them both and flush the heater core in both directions.

(chk the valve as RRR mentioned at the same time, as I'll bet these two checks will give you your answer)
 
when I first got Ginger she didn't have any heat either (still doesn't but that's another story)
I didn't think nothing of it, because I had bigger fish to fry

when it was time to yank out the /6 to make room for a 360 I disconnected the heater hoses only to find an allen head bolt lodged in one of them
my guess is she has a leaking heater core, and someone though this was great way to stop the leak
 
RustyRatRod said:
Sounds like a vacuum issue. Look under the hood over by the heater control valve is. Look at the vacuum line going into the valve. They are bad about rotting and even sometimes falling onto the exhaust manifold.

Also look at every other vacuum line you can find. Something is either rotted and leaking or disconnected and leaking, causing the blend doors to move from lost vacuum when you accelerate.
Click to expand...

I don't think my truck has a heater control valve. My heater hoses come out of the firewall and go straight to the engine block. I could be wrong, though. I'm not a mechanic, and I surely don't know everything. I'll still have a look at the other lines I can find and see if anything is messed up. Thanks for the suggestion.

69FBCuda said:
Check the input and output hoses are both getting hot ?
Click to expand...

TrailBeast said:
X2
An easy way to tell if you have a flow problem.
If one hose is good and warm and the other is cold, then disconnect them both and flush the heater core in both directions.

(chk the valve as RRR mentioned at the same time, as I'll bet these two checks will give you your answer)
Click to expand...

I did feel the hoses after I swapped the thermostat and let the truck warm up. The inboard hose was really hot and the outboard hose was lukewarm to the touch, at best. Personally, I think I'd rather just swap the heater core with a new one. They're only $25+tax, and it takes about 30 minutes with my truck. Undo the clamps on the heater hoses and pull them off, pull clips out from under the dash and remove a trim panel, pull four bolts off the cover to the heater core, and then just pull it out. To put the new one in, just rinse and repeat. I'll let you all know how it turns out.

Thanks everyone!
 
Possibly your E9TZ 19A523-A vacuum switch... They were only about $26 from ford unfortunately it is an obsolete part but an internet search may find you one.
 
It doesn't have to be the heater control valve. Don't zero in on that. It can be a vacuum malfunction anywhere and that's what it sounds like.

Vacuum is used in the HVAC box to "do" things. Operate blend doors and such. When you have a vacuum leak and accelerate, the vacuum goes away and "undoes" whatever it is that it's supposed to be "doing".

You have good vacuum at idle. Vacuum normally drops off on acceleration. Vehicles use vacuum canisters to help keep vacuum up to operate accessories like the HVAC system. When there's a leak, those accessories will fail on acceleration.

This is a very, very common problem with Fords along your year model. My 04 Ranger had the heater control valve rubber end rot off and do the exact same thing.

Once again, it does not have to be the heater control valve. It can be ANY vacuum hose or line under the hood or under the dash. The vacuum system is all connected so a leak will affect it all.
 
Sometimes guys will fix this by adding a vacuum reservoir and check valve to the system.
 
If you think the core might be it, you can try back flushing it. They do sometimes stop up. But that does not explain why the heat goes away on acceleration. Back flushing it would be a LOT easier than replacing it since the dash has to come out.
 
If both heater hoses going into and coming out of the heater core are getting hot about the same time it is less likely the heater core is the problem. It wouldn't hurt to back flush it and see how it flows though.
 
RustyRatRod said:
If you think the core might be it, you can try back flushing it. They do sometimes stop up. But that does not explain why the heat goes away on acceleration. Back flushing it would be a LOT easier than replacing it since the dash has to come out.
Click to expand...

If it doesn't have a control valve AND the hoses are quite a different temp then that just increases the chances of it being a plugged up core.
Seems to me anyway.

And heat going away at acceleration could just mean it goes away with more air flow over the core and getting heated less due to the increased volume. (maybe)

Another one of those 10 min to figure it out if we were actually there things. :D
 
Maybe. Keep in mind though, that the heater core is a small radiator. It's perfectly normal to feel a pretty noticeable difference between temperatures in the inlet and outlet.
 
RustyRatRod said:
Maybe. Keep in mind though, that the heater core is a small radiator. It's perfectly normal to feel a pretty noticeable difference between temperatures in the inlet and outlet.
Click to expand...

Yep, it takes experienced feelers.
 
RustyRatRod said:
If you think the core might be it, you can try back flushing it. They do sometimes stop up. But that does not explain why the heat goes away on acceleration. Back flushing it would be a LOT easier than replacing it since the dash has to come out.
Click to expand...

Luckily, that's something I don't have to worry about. On my model of Ranger (1992), the heater core is about a 30 minute job. The dash doesn't have to come out. It's accessible behind a trim panel under the glove compartment.

I am not discounting anyone's suggestions. I will take a look tomorrow when I get a chance. Thank you to all for your suggestions, and I'll update as soon as I have more information.
 
You might be right about the heater core under idle antifreeze pressure is low allowing coolant to go through a semi-clogged core. Under more rpm drive antifreeze pressure up it takes the path of least resistance and bypasses the core through the built in bypass in the core. It is kind of common on Rangers. I had the same problem with our shop truck. There is a product sold at GM dealers that will clean a cooling system it is largely made of phosphoric acid. It does an awesome job of cleaning but it will also be deadly to weak gaskets.
 
Ford vehicles from the 90`s tend to plug the heater core and cause your problem. It is way more common than most think. It is the way the system is designed and causes all the crap to plug the core.
 
Here is my two cents worth. I think it boils down to two things.
1) Is the engine heating up? If you do not have a temp gauge that you are 100% sure of, but a laser thermometer. They sell them for as little as $40 and they are VERY handy. You will wind up using it a lot. That way you can accurately determine if the engine is warming up. The easiest way is to check the temp at the thermostat.
2) Next, (assuming the engine is warming up properly) you need to determine where the hot water break in continuity is. For example, if everything up to the firewall is 180 degrees and the heater hose coming out of the firewall is 80 degrees, the heater core is plugged (assuming it isn't leaking). That is when backflushing it (Forcing water through it backwards of the normal flow) will work well. I did that in a Dodge Caravan once, and you should have seen the crap that came out. The heater worked much better after that.
 
Just a quick update... I pulled the cover off the heater core, and liquid immediately started running out. My first thought was, "Great! There's the problem!" However, as I got to looking at what was running out, it was just water. No antifreeze smell, not dirty. Clear water. It rained all day yesterday, so apparently I've got some runoff from my cowl getting into my heater box. Heater core itself looked okay, so I figured I'd go ahead and flush it. Yeah, that ain't gonna happen. At least, not easily. I got to looking at the condition of my heater hoses, and they're gonna need replaced. Knowing my luck with Ford OEM hose clamps, at least one of the hoses is gonna get cut off. That could possibly be a big part of my problem, too, if they're all gunked up inside. I'll replace them and then flush my heater core and see if that fixes anything. Thanks again for all help offered.
 
You must log in or register to reply here.
-

Back
Top