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Intermittent Heat

2K views 21 replies 5 participants last post by  hg3300 
#1 ·
Okay, so it's almost November and I really don't want to be without heat for the winter...

Most of the time I am unable to get hot air from the vents but sometimes I can feel it working. I had a similar issue with the AC where most of the time it was cold but over the course of a drive would get a bit warmer then cold again. I suspect that whatever is causing both of these issues is the same.

I have read about diagnostics (how to get the trouble codes, but the tutorial was obviously not written for my model because I only have two buttons: the A/C compressor and rear defrost.

The instructions tell me this:
"On cars with manual climate control(MTC), set the blower to any speed, turn the temperature control in between warm and cold. Press Floor, Defrost\Floor, and Front Defrost. All codes will flash via the Front Defrost button."

I've been told that I could try changing the thermostat but I'm not sure if that's the issue. Plus the temp gauge in the instrument panel seems to work fine.
 
#2 ·
This is often a symptom of low coolant/trapped air in our cars. Make sure to thoroughly bleed and top off the system exactly per the instructions in the FSM. It's important to overfill by the procedure. You can accomplish that using a tapered funnel to seal to the reservoir/pressure tank fill hole.
 
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#5 · (Edited)
Whoa! PEVA is talking about the engine coolant! (Also referred to as Antifreeze, etc) NOT the A/C Refrigerant. Zerex G05 is what you need.

Your heater issue is most likely due to an air pocket or bubble in the engine cooling system. It's common for this problem to show your symptoms due to the coolant not circulating to the heater core and no heat.

You also need to verify that you have no leaks in the cooling system. When was the last time if ever you checked the Coolant Level in the reservoir? That's the plastic tank under the hood on the drivers side near the firewall with a radiator cap!
 
#7 ·
Okay, so I found the correct instructions to do diagnostics on the HVAC system and it threw AC 23, which I'm reading is the Blend Door actuator and I'm also reading it's the most difficult part in the system to get at, so I will be having some fun later this year replacing it.
 
#8 ·
And I know this probably isn't related, but the car wouldn't start after I drove it to the auto parts store to get some Zerex G05 coolant. I was going to get spark plugs too but the car hasn't been stalling/hesitating and the engine light is off. I figure if it happens again I'll replace them.

Not sure why the car wouldn't start, I tried several times, gave it a little gas, which didn't help. I let it sit for 5-10 minutes and it started right up, albeit a little rough. I let it idle for a bit, and gave it a little gas, and the roughness went away. I could be wrong, but I don't think diagnosing the HVAC system could cause this. As I said, the check engine light isn't on, so I have no educated guesses to what caused this. My mechanic uncle suggested a few things like the cam sensor, idle air controller, and fuel pump, but obviously cannot diagnose the issue remotely.

I'm probably going to take it down to a dealer tomorrow to have them take a look, I'm just hoping it's not something like the head gasket because I know that's an expensive fix and a lot of work to do yourself.
 
#10 ·
lol Ron calm down, I already knew what coolant to use when I was advised earlier in that thread. I was less worried about it because I had other issues with the car at the time. I only bring it up now because I'm finally trying to fix the problem.
 
#15 ·
I went to NAPA for it. It looked exactly the same as the one I took out.

Funny thing is, after I bought the CarFax report for it, turns out it was already replaced back in April.
Just saying, that might be part of your problem. OEM sensors from a mopar dealer have been highly recommended because they are pretty much the only ones that consistently work. But if you want to spend the money on multiple aftermarket sensors when there's not much difference in the cost of OEM, then its up to you on how you spend your money.
 
#17 ·
Engine speed/position sensors, oil pressure switch, coolant reservoir, strut mounts and bearings, radiators (tough call, OEM is $300 and an aftermarket is about 70). Aftermarket radiators seem to be bad out of the box or last up to 30,000 miles give or take a few. Lower control arms and strut rod bushings, window switches (from what I've seen the OEM window switches are cheaper although I just go to the hard to get them if/when needed). Waterpump and tensioners for 2.7L engines.
 
#19 ·
Update on the situation: MAJOR issues. Car wouldn't start for about 5 minutes after stopping at an auto parts store. Next day going to work it stalled at a stoplight and again I had to wait 5 minutes. Coming back from work it stalled pulling into a gas station and seemed to let off a bit of steam. Sat for an hour, put gas in, drove it home.

Today, drove the car to the grocery store, then started off to work again. Car started losing acceleration on the interstate and steam appeared to be coming from the back (but that may just be steam from the front as I was driving 70-80 mph). A few lights came on briefly, the oil and coolant lights as well as check engine, and the car stalled as I pulled to the side, while steam pour out the front and fogged up the windshield.

After letting it cool down, I checked the engine to get an idea what happened, and I found the oil was low (nothing on dipstick) and coolant was empty. Cop came by to pull me off the road a bit more and place flares and we found a bunch of oil on the side of the road where I pulled off.

So obviously I lost oil and possibly coolant (I wouldn't be surprised if the latter was the cause of my A/C issues at this point) but I am not sure from where or what exactly may have been the root cause.

Obviously the car overheated, that much I'm sure. I am not sure why oil leaked out though. It was suggested that if I have an oil cooler that a hose in that area may have been the culprit. Can anyone shed some light on this and give me suggestions on where to look for issues? I'm hoping to get this car back up and running, but as of right now there's no compression.
 
#20 ·
This being a 2.7, I don't think it has the (radiator tank) oil cooler.

Common exterior coolant loss points are radiator side tank split (usually vertical split on rear of passenger side tank), coolant reservoir/pressure tank cracked (or bad cap seal), coolant outlet housing (metal bleeder debonded from top, or top separated from body of housing), a ruptured or loose radiator or heater hose.

Possibly the water pump leaked coolant into the engine, mixing oil and coolant. Not sure that jives with all that you've described.

If it's truly oil on the side of the road, lots to speculate. Threw a rod? If you measured compression, it seems that that would have been obvious. Oil pressure sensor switch, but usually that is more of a drip rather than a stream. Oil filter got double gasketed? The water pump-leaking-into-the-crankcase scenario, and what you saw on the side of the road was oil-water mix from huge coolant system leak? Or was it not oil?
 
#22 ·
Those are all good speculations, I'm not sure which one is what happened but I'll be sure to try to check for all of them when inspecting the car tomorrow.

I'm not sure about throwing a rod, but only because the last time that happened to me was in my 99 Cav and it was really loud right before it happened. There was no warning this time, of course I could be wrong and it being a different engine makes all the difference.

It was definitely oil on the road, from my car, (the officer and my father smelled it) but I can't be sure whether or not there was coolant (or water?) mixed in with it.
 
#21 ·
One more thought on oil: oil pan issues - cracked, or stripped drain plug hole threads, but those would usually be drips rather that sudden dump, unless plug fell out or something.
 
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