Runs hot when ac is on

So I bought a mint condition 06 dc the other day and I noticed that it got warm while sitting in dead stopped traffic on a 100* day with the ac on. I turned off the ac and it cooled down. So today I put the ultra gauge off my 00 tundra on my new 06 today and let it sit in the shade with pretty high humidity but only about 85* and let it idle with the ac on for about 10-15 min and the instant read out on the ultra gauge showed it climb to 212 before I turned off the ac and let it cool back down. My 00 never got anywhere near 200 unless I was towing up hill in 100*. So what would cause this one to run hot only with the ac on? The first time I noticed it was in a traffic jam and the ac got hot so that perked my attention and the trucks heat hand was at 3/4 into the hot or a little more but it took it probably an hour to get that hot. The guy said the timing belt was done about 5k miles ago along with water pump. Everything under the hood looks like a new truck. Nothing shows age at all. Has plenty of coolant also.

 

I'd check that the cooling fan is coming on and working properly. After that, check airflow through the rad/cond isn't blocked. Then, proper coolant level/condition/flow.

 

Trans fluid fresh?

 

I believe that truck has a fan clutch on the cooling fan (Mechanical not electric) if so I would check and make sure its working properly - they usually get weak after a while and no longer lock up as the temp starts to rise so you dont get the correct cooling

 

I've never owned a First Gen Tundra, but I have owned an older Toyota truck which had an "idle-up" solenoid that increased idle speed to compensate for the added load of the AC compressor engaging. If the "idle-up" circuit isn't working, your AC efficiency and coolant circulation will be reduced. Check to see if your idle speed is sagging when the compressor engages. Set idle speed to specs as described in the Service Repair Manual.

 

I’m not sure, previous owner did change it at some point according to Toyota records but I can’t remember how long it’s been. I’ll have to check.

 

I popped the hood while it was warming up yesterday just to see if the fan was on and it was. So can it be on but not be on good enough? Or is it like it’s either on or not?

 

Anyone know where I might locate this circuit?

 

I’ve pretty much done all that. That was everything I did before getting a little stumped. I mean I can’t tell how well the coolant is flowing but the radiator looks great. If the water pump wasn’t working I’d have bigger issues. If the thermostat wasn’t working then it would cause issues other than just when the ac was on.

 

The solenoid on the old 22RE was mounted right on the valve cover, and worked by opening a vacuum port into the throttle body. On the newer trucks, I think the idle-up function is possibly handled solely by the ECU.

With a bad solenoid, my 4Runner's idle speed would drop from about 750 to around 500-550; it would barely idle with the compressor engaged. It did not overheat, but it knocked the AC in the dirt.

 

Does your fan make a loudish roar type noise while this is happening? Like after idling and being in traffic?

 

yes it can be a weak clutch on the fan - they get tired after a few years - the old test back in the day was with the engine running stick a piece of heater house against the fan - if the fan stops the clutch is no good !

 

It uses a fluid to "lock up" and they just get weak over time. At 14 years old it's not going to hurt to replace.

Should be built in to the computer programming. Turn the A/C off, watch the tach and turn the A/C back on. You should see it bump up a couple hundred RPM. I know on my 04 sitting at a stop you can tell when the A/C compressor starts running especially if you aren't holding the brake hard.

Possible the radiator has some internal corrosion blocking some of the pathways since you don't know if it's original to the truck. If it only does it at a long stand still it may just be a combination of the fan clutch/radiator being older and on the "marginal" end where it works well while your moving but not so well at a stop.

 

When my A/C kicks in my RPMs jump up about 150 when at idle. I believe this is spec in the manual.

 

Does the temp go down of you switch from AC to heat? Sounds like a thermostat to me.

 

Well I think I figured it out. All seemed ok with the clutch once I removed and compared it with the new oem one I bought. I replaced the radiator with an oem one and at the same time I replaced the thermostat. Don't know which one fixed it but I replaced everything I bought for it except the clutch because it felt just as good as the new one. Temps stay between 185 and 190 now.