97 Disco overheating

[gogodisco]

My disco is overheating when I have the a/c on only. I have checked the coolant level, replaced one of the two fans in front of the radiator and it still starts to overheat after driving for awhile with the a/c on. What else should we check?

 

[SteezTight]

Have you bled the system to check for air bubbles in the radiator?

 

[wolf]

I had this happen on my 1997 Disco after a serious towing job - it turned out my thermostat was freezing closed then open. Replaced it - bled coolant system for all bubbles all over-heating problems went away. It worked great - even in S. California in the summer - in traffic/freeway - whatever - and all without the viscous fan not operating. I replaced that when I got back home from California.

In my case - it had nothing to do with the AC it's just that it was so close to heating up that the AC load triggered the issue. This may be the case in yours - but you need to check that AC unit's pulley as well and proceed from there.

 

[antichrist]

Aside from what's mentioned above....
Make sure your radiator isn't clogged with debris. Take your garden hose with sprayer attached and stick it down between the fan and radiator and spray. Bugs, leaves, seeds etc will clog the fins and cause over heating.
If that doesn't fix it, check your viscous clutch to make sure it's good. Try turning the fan by hand with the engine cold. Then drive it until it reached operating temp. Shut it down and try turning it by hand again. You should get more resistance.
If that checks out, take your radiator to a radiator shop and have it rodded. It could very well be clogged internally with crud.

 

[gogodisco]

Ok, we have rodded the radiator and in the mean time the a/c went out and it took awhile to figure out we had a leak in one of the rear a/c pipes (over the rear tire). That is all replaced now, a/c is charged, no air bubbles in rad and I have two problems. 1. Rear a/c blows warm 2. Engine is still overheating with a/c on, but inconsistently. Now what?

 

[Disco Mike]

Things to look at, t-stat, both electric fans, the mechanical fan clutch.

 

[gogodisco]

Thanks Mike. The fan clutch turns but with some resistance, should it free wheel? What should be the temperature rating on the thermostat?

 

[Disco Mike]

T-Stat is 180.
The fan should free wheel with a slight resistance when cold and have alot more resistance when hot.
Are both your electric fans running with the a/c on?