Overheating When The A/C Is On

[GoingGreen]

Aloha everyone. I searched around but couldn't find the answer I was looking for.

'06 Limited, 2.4 NA

My Cruiser started overheating the other day, but only does so if the A/C is turned on. I can have the fan portion turned on (just air), but if I click on the A/C button, the engine bogs down heavily every 30 seconds or so and the needle steadily climbs. Goes right back down when I turn off the A/C. This happens when parked or driving.

Side note, I have to put coolant in the radiator every couple of weeks, gets low quick but I don't see it pouring out anywhere.

Any suggestions is greatly appreciated.

[CREWZIN]

Sounds like the typical fan malfunction but also something else with the missing coolant.
One, you want to find out if both speeds of the fan are working and two, you need to find out where the coolant is disappearing to. Possible a small crack in the head gasket which will let coolant slip into the combustion chamber and get burned off. You could also have a small leak somewhere that will let the coolant drip onto a hot surface and be burned off so you won't see anything on the ground. You shouldn't be loosing any of the coolant if everything is running right.

[GoingGreen]

Thanks Crewzin. It didn't occur to me that the coolant might be evaporating on a hot surface. I had the fan replaced about a year ago, but run up to the shop to have them test the connections.

Thanks for the reply. Hoping for something relatively simple.

[Busted_PT]

I agree with CREWZIN . Some spots to look at are the plastic water neck that fits over the t stat , cap and hose connections. Look for whitish streaks. The water neck is famous for cracks. Also radiator is a possibility.

[GoingGreen]

Thank you two, I appreciate the input.

I did the key dance, and could only get a code to appear once. Each time I try afterwards, it always displays DONE.

The code was P0638, which shows Throttle Actuator Control (TAC) Command Performance. I'm unsure of what that is, but as I stated in my original post, my PT bogs down heavily (almost dies) when I click on the A/C. Could this be the culprit?

[CREWZIN]

I'm at a loss on this one. My search turned up nothing on the P0638 and having the car almost die with turning on the A/C doesn't make a lot of sense unless the computer itself isn't recognizing the A/C is on to compensate by raising the idle.

[mdfrodolives]

Well, when my fan was going out, there was no indication of it until I turned on the A/C. Then all hell broke loose: The sputtering/almost dying at idle. So the one problem might just be the need for a new fan.

The coolant loss is another matter. Hopefully, it's just a leak somewhere around your thermostat housing cover (the black pipe with the radiator cap sitting on top). The cover/pipe itself, or, more likely, the flange where it jins the thermostat housing.

Have you checked your oil lately? Is it milky? Hopefully, not.

Tim

[GoingGreen]

Thanks for your input mdfrodolives. I haven't had the chance to do much investigating this weekend, been doing some family-time. I'll make sure I look at the oil and look for some leaks, it has to be coming from somewhere, just hoping for something simple.

Thanks again and I'll provide an update tomorrow.