I am hoping someone here can get me on the right track. Let me build a small back story.

The vehicle is a 2006 MCS that just hit 100k miles. My wife took the car to a local car wash and while driving home the car was on the verge of overheating. She took the car out later that evening and she didn't make it more than two miles before it overheated.

So here is what I just performed hoping everything would be fixed:
1. Replaced water pump, thermostat, t-stat housing, all associated seals and gaskets along with hoses.
2. Changed S/C oil
3. Replaced coolant
4. Replaced low speed fan resistor (replacement unit mounted to fan housing)
5. Replaced high speed fan relay (green relay located in fuse panel next to airbox)
6. Checked all fuses that would be related (nothing was blown)

After replacing all of the above I am having the following problems:

1. The high speed fan along with the PS steering pump fan does not come on; even with the A/C turned on
2. The low speed fan doesn't kick on
3. The car is blowing cold air while set to heat
4. Coolant does not appear to be flowing through the system (the upper radiator hose is not getting hot, but the coolant in the expansion tank is boiling)

One thing of note, when I jump slots 30 & 87 where the high speed relay connects, both the high speed fan and power steering pump fan operate.

When I jump the same slots on the low speed relay, the fan does not operate; however, I get a clicking on the Heater/AC relay located in the driver side foot well fuse panel.

Could this relay be bad?

I am thinking it is something electrical that may have shorted out during the car wash.

Any help or suggestions is appreciated!

- Joe

 

Wow, seems that you've been very thorough.

I don't have much to add, but it sounds like you need to bleed the coolant system a bit better using the two accessible bleed screws (Front & Center on upper rad hose, and to the right of the MAP sensor over by the thermostat)

Failing that, yes, change out the relay (though I've never heard of them going bad/damaged)

Good luck!

 

Out of town right now, but I plan on getting back at it this weekend. I've read the entire low speed resistor thread (perhaps I should have posted there). I found the thermostat bleed screw and was able to burp a bunch of air out of the bleeder. Maybe an air pocket was preventing the heater from blowing hot, but not sure about why the fans aren't running. Could it have something to do with the A/C compressor coil being bad?

 

I cant help you with your fan issue, but if the water isn't flowing correctly that is separate from the fans anyway.

Was there oil in the sc when you drained it? Or did you look at the sc gears to make sure they were ok if no oil came out?

And like Jamez said, make sure you have bled it as good as you can, use that bleeder screw by the radiator too. You need to get all the air out because that will also make your car overheat.

 

Thanks for the reply. The supercharger was in great shape and both ends were full of oil, funky smelling oil, but oil nonetheless. I am going to throw the car into the setting that shows coolant temps in the cluster and let it run through all the temp trigger points to see if any fans kick on.

 

If the coolant isn't flowing you've either got an inoperable waterpump, or a thermostat installed backwards (which is near impossible to do with the factory housing).

When you are doing this heat cycle is it still in the garage or are you driving the car? Did you remove the pin used to lock the belt tensioner so the belt could be removed?

Stupid I know, but there is coolant in the car and bled properly, right?

The low speed not working will probably come back to the resistor you wired in, either the wires were mixed up or there is a loose wire. I've had to warranty a couple Dorman resistors with our supplier due to the wires just falling off the resistor board during install.

 

Valid questions but I verified the water pump impeller spins when the supercharger is turning. The coolant is an OEM 50/50 mix, the thermostat is definitely installed correctly and the belt was recently replaced and is routed correctly.

I was aware of the poor Dorman quality, so I reinforced the wires before installing the resistor. The low speed pin on the harness ohms infinite, the high speed gives me a reading of 7.

I'll be back at it tomorrow after traveling home.