I have a couple of nagging issues with my truck, a few of which are AC/heat related. Those include:

1) I've noticed that the AC clutch engages very frequently while I'm running the heat. Is this normal? (it seems like that should not happen)

2) About a month ago, I was driving with the heat on when I started smelling the distinct odor of burning leaves. The cab got warm, so I turned off the heat for a bit, but when I turned the fan back on later, smoke started BILLOWING out of all the air vents and filled up the cab. Thankfully I was almost at my destination when this happened, so I immediately turned off the fan and ignition, jumped out, and frantically started trying to remove the fan motor from under the dash, assuming that some leaves had gotten caught either in the fan or on the heater core and ignited. However, I couldn't get one of the screws out with the tools I had on hand, so I had to just sit and wait. Thankfully, the fire seemed to put itself out. I later removed the fan motor and could not find any evidence of burned leaves/debris, although the coil fins inside the ductwork just above the fan motor were clogged pretty good. Has anyone else ever had something like this happen?

3) This is an unrelated issue, but I am having an ongoing issue with a leaky thermostat housing. I have replaced the thermostat gasket several times to no avail, and when I had my plenum off this summer, I installed a new thermostat housing thinking maybe the old housing was warped/corroded and wasn't sealing. That seemed to solve the issue for a while, until today I noticed some damp spots on the ground below my truck. I started looking around and discovered I still have a coolant leak, most likely either where the upper radiator hose attaches to the housing, or where the housing bolts to the intake manifold, as there is a bunch of dried up coolant/corrosion on top of the thermostat housing flange and running down both sides of the front of the engine. Any suggestions? I've been using the paper gaskets...should I use some RTV gasket maker instead?

Thanks in advance for any advice you can offer!

 

for the leaky housing, always use fel-pro gaskets man, on coolant gasket i tend to use the gasket and also throw a thin layer of rtv on it. personal pref i guess. the ac clutch engaging, i saw a post awhile back about the same issue you may be able to search and find it. the burning smell, could it had been insulation burning?

 

Try a cork gasket they seem to work well against coolant leaks.

 

1) If you are using the heat with the vent selector on defrost or defrost/feet then the ac clutch should be cycling. The compressor serves to remove moisture from inside the cab and therefore defrost the inside of the windshield. As long as you are using the defrost function, this is normal behavior.

2) No idea

3) The thermostat housing set-up on these trucks is, in my opinion, a poor design. The upper rad hose comes straight down onto the housing making it very easy for a leak to develop. Make sure you have either a constant-pressure (factory style) clamp on the upper rad hose or a sturdy hose clamp cranked down very tight (use a socket and ratchet, not a screwdriver). For the housing gasket, I use some high temp RTV along with the felpro gasket to prevent leaks. Has worked for me so far....I also had a terrible thermostat housing leak when I first bought my truck. Quite frustrating.

 

Cool, yeah when I repaired the plenum I thought about using some RTV on the thermostat housing, but didn't want to have to deal with cleaning it off if I ever had to remove the thermostat again. I should have used the RTV. Oh well, live and learn.

Thanks, I'll do some more searching about the AC clutch issue.

With regard to the burning smell, it was the unmistakable smell of burning leaves. I'm pretty sure burning insulation would smell like burning plastic/rubber. I am convinced that there were leaves that caught on fire somewhere in the duct system. I have definitely pulled clumps of leaves out of the blower motor before. It seems weird that there is no cabin air filter to keep debris like that from getting into the system...

Thanks for your input.

 

Thanks. Does FelPro make a cork gasket?

 

That makes sense. Unfortunately, in my case the AC clutch seems to engage no matter what setting the vent selector is on. I mainly notice it when I am only using the heat. That definitely seems abnormal.

No problem - me neither! I'm going to keep looking. I want to pull the blower motor resistor out to see if I see anything there. I definitely found a lot of leaves in that area when I replaced the resistor a couple years ago.

I agree with you there. I'm really wondering if the hose-to-housing connection is where my leak is coming from, simply because I can see a bunch of dried coolant on top of the housing flange, which has a lip all the way around it. Unless coolant is leaking around the flange bolts and pooling on top of the flange, I'm guessing it's getting out from the upper radiator hose and running down the housing. I do have a hose clamp connecting it, and I tightened it with a ratchet...but I'll have to check it all out.

I'll definitely use some RTV when I replace the gasket this time.

Thanks!

 

might be a little overkill but maybe put 2 clamps on it?

 

If there is room to get two clamps between the end of the housing outlet pipe and the rib on the housing outlet, I just may do so. Good idea.

 

OK, stupid question - do you use RTV both between the intake manifold and gasket, as well as between the gasket and housing?