Ac Serviced...now Engine Overheating!

[waf102]

Yesterday morning I had my ac serviced. They added about a pound of refrigerant to top it off and said it all seems to be working fine.

I drove it around for a while afterwards with the ac on...just to test it out...I had it set to the lowest temp. (FYI...before this I haven't run the AC for more than 5 minutes for years.)

Then I began to notice that the temp gauge (which I believe doesn't work to spec...or its sensor doesn't - as it never moves above the first line above) starts jumping up and back down as I go up hills and down again. I finally get home and start to see antifreeze leaking from the front drivers side corner of the car.

I looked around and it appears that the coolant has come from the over flow hose that is connected at the top to the overflow coolant tank.

So...while the temp gauge doesn't give an entirely accurate reading...it is overheating...as coolant is overflowing.

Soooo......you think this is a coincidence? Could those guys messing with the ac done something to cause this?

What are the candidates for causing overheating out of the blue? There are no noticeable noises or other leaks...so it ain't the water pump.

???

[Ruud]

Hi,

I think most ppl are stumped, incl me. :)

It might be an idea to get your temp sensor fixed in the first place and go from there..

My old '93 ls used to spill some coolant from the expansion tank even on normal operation temperature.

[eatingupblacktop]

Find out why your temp guage isn't giving you proper reading (gauge-coolant temp sensor?)

Check your reservoir cap doesn't need replacing.

Check coolant level

Check coolant pressure (partially blocked rad/system - water pump)

Check air flow through your rad (leaves/debris between rads)

Check fan is working properly

Check tension on your s-belt

Check a/c is cycling properly and isn't on all the time

[curiousB]

Soooo......you think this is a coincidence? Could those guys messing with the ac done something to cause this????

Doubtful as topping up AC is pretty simple. Did they say they did other things in addition to AC top up? Maybe a simple test is to see if you get this strange behavior with AC shut off. If so and all they did was a refrigerant top up then I think its likely unrelated and just coincidence.

[fsuguy]

Yesterday morning I had my ac serviced. They added about a pound of refrigerant to top it off and said it all seems to be working fine.

I drove it around for a while afterwards with the ac on...just to test it out...I had it set to the lowest temp. (FYI...before this I haven't run the AC for more than 5 minutes for years.)

Then I began to notice that the temp gauge (which I believe doesn't work to spec...or its sensor doesn't - as it never moves above the first line above) starts jumping up and back down as I go up hills and down again. I finally get home and start to see antifreeze leaking from the front drivers side corner of the car.

I looked around and it appears that the coolant has come from the over flow hose that is connected at the top to the overflow coolant tank.

So...while the temp gauge doesn't give an entirely accurate reading...it is overheating...as coolant is overflowing.

Soooo......you think this is a coincidence? Could those guys messing with the ac done something to cause this?

What are the candidates for causing overheating out of the blue? There are no noticeable noises or other leaks...so it ain't the water pump.

???

waf102,

having your a/c on puts additional demands on the engine. If you have not used the a/c much, and are now experiencing overheating, there is likely another underlying problem. How does the engine idle w/o a/c on? If some cylinders are not firing - old plugs, wires, rotor, cap, etc., then the additional demand on the engine will cause overheating. Check these, incuding timing, and let us know what you find out.

B)

[waf102]

Thanks for the replies....

The engine is running well...get good gas milage...good sign.

But the mechanic says the thermostat needs replaced and the resevoir has a crack that expands under pressure.

Hopefully that is all it is.

Thanks again guys!

-Bill

P.S. ANy one know the part number for the one-wire water temperature sensor near the thermostat?

[fsuguy]

Thanks for the replies....

The engine is running well...get good gas milage...good sign.

But the mechanic says the thermostat needs replaced and the resevoir has a crack that expands under pressure.

Hopefully that is all it is.

Thanks again guys!

-Bill

P.S. ANy one know the part number for the one-wire water temperature sensor near the thermostat?

Hi waf102,

try this link: http://www.toyodiy.com/parts/p_U_1992_LEXU...PGKA_8401.html; the part listed is 83420-16020/16050 depending upon your vin#.

[Mike Floutier]

Although this is an old thread I thought it would be good to add my symptoms/question here with a view to gathering related info together for future reference.

As some may remember my 2002 LS430 (now with 320,000 miles) has a gradually worsening mis-fire, now on a couple of cylinders, caused by valve seat recession due to driving many miles on propane.

My temp gauge has always been solid on the mark just below the horizontal BUT recently it has been edging up, either half or a whole mark, where it sits solidly for a minute or two before returning to normal.

This has only happened during high engine/ambient temperature situations.

I noticed the comment in the earlier conversations about the increased engine temperature attributable to mis-fire situations and this made me sit up.

I guess I may have a problem with the Thermostat - is this easy to get at for testing?

Also I suppose the fan(s) may be at fault; is there a good way to test them?

Thanks for your help.

Regards,

Mike

[lenore]

generally when you turn AC on both fans should come on with the compressor cycles.

[landar]

I would first make sure that you are not marginally low on coolant by viewing the reservoir tank. You could have some air in the system. The thermostat is fairly easy to replace. I would not bother testing it. If you go to the trouble to remove it, just put a new one in (along with a gasket). Also, coolant should be changed every 120km or so (or few years).

[Mike Floutier]

Thanks Guys, for some reason I thought the thermostat was very inaccessible - must have been thinking of the water pump.

It's been on the car for 321,000 miles so I guess in the very hot weather we're experiencing here in the UK it has every right to complain a little.

I've ordered a new one and let you know how it goes.

Many thanks.

Mike

[AzHotLS]

How do the coolant tank cap gaskets look? You may want to replace the cap while your at it.

Also consider replacing the drain plug. It could be brittle and break when you drain some coolant before removing the thermostat. You do want to drain some otherwise you'll get quite a bit coming out, all over your serpantine belt. That means you'll need coolant too.

Just did this on my 95 this past Monday.