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Guest Message by DevFuse

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overheats with the A/C on

1987 GL-10 Turbo wagon a/c overheat

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8 replies to this topic



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Posted 29 June 2013 - 02:53 PM

As the temperatures here in Utah have hit well over 100 degrees for the past couple days, my GL-10 has started having trouble keeping its temp down. I've been very cautious and kept a close eye on the temp gauge on the dash to make sure it doesn't overheat. I've found that it stays cool just fine even at highway speeds without the a/c on, but with the A/C, the temp goes up fast and I have to turn it off again to keep the car cool. Does this indicate that I need a new radiator? Is there something I can do to get it to keep cool even with the A/C or is this just how it goes with an '87? I'm gonna flush the fluid one more time and see if that helps. any recommended brands for coolant?

#2 l75eya


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Posted 29 June 2013 - 04:59 PM

Is your electric fan (pass. Side fan) turning on when you engage the air conditioner?



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Posted 29 June 2013 - 05:07 PM

no it does not. I tried with both the A/C and the heat, and although both work well (the blow really cold and really hot) the electric fan does not engage. What does that mean?

#4 scoobiedubie


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Posted 29 June 2013 - 08:59 PM

Could just have a loose connection to either the radiator or to the auxiliary fan. Or the silver round fuse type plug-in thingamajig above your knees and inside the dash, could have been fried. You can pull one at a time and check for melting. There are about 8 of those silver round plug ins to the left of the steering wheel and beneath the dash. You also could have a mouse nest between the A/C radiator and the main radiator. Normally, you need a double core radiator for GL-10's when you run the A/C in the summer time. Your old radiator probably has a gunk build-up inside that causes things to now get hot, when they had worked OK in previous years. It also helps to take off the two gravel guards that sit below and to the left and right of the engine. This will increase the air cooling of the cylinder heads so the coolant does not have to do the entire job. You could also get a thermosat that runs about 10 deg F cooler than stock, and use it only in the summer time.

#5 jeryst


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Posted 29 June 2013 - 09:14 PM

My 1990 Loyale wagon was overheating when the AC was on.

II noticed the fan wasnt coming on. I started wiggling wires around and the fan started working.

It now does not have any problems overheating no matter how hot it is and how long I use the AC.

Probably a little corrosion on the connector.

#6 SmashedGlass


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Posted 29 June 2013 - 09:32 PM

Question: have you ever seen the electric fan operate on it's own? If not, you first need to check to see if it even works; you can do this with the car off.

Simply unplug the fan's two-wire connector, jam a few feet of wire with stripped ends into each slot so you have a pos and neg wire to work with, then touch the ends to your battery pos and neg posts. If the fan doesn't turn, it's toast.


If the fan works with 12v supplied to it that way, then you can start checking to see if it's the temperature switch or possibly even the trinary switch going bad. Could also be minor shorting in the wiring around those two--I once was able to make my fan turn on and off simply by moving the wiring around a little bit due to a small chunk of insulation missing from one or two of the wires in that system.


***I see jeryst mentions the same thing happening to him, while I was taking my sweet rump roast time typing this :D

Edited by SmashedGlass, 29 June 2013 - 09:33 PM.

#7 Gloyale


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Posted 29 June 2013 - 09:42 PM

The relay mounted under the vacuum canister on the pass. side strut tower should turn on the fan on anytime hte A/C is on.  Remember, when this relay closes it supplies ground to the Fan....not 12v.


Check to see it's getting power to the coil side.  If not, then Check for 12v on the trinary switch R/y wire IIRC, not the blue ones.  If there is power going in, but not coming out of the trinary switch that's the issue.


IF no power there, then you need to check the supply circuit.


Is this a turbo car?  If so you have the Panasonic/matsushita setup and not hte hitachi....correct? ( You're Alt is outside of the compressor?)

Edited by Gloyale, 29 June 2013 - 09:43 PM.

#8 l75eya


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Posted 30 June 2013 - 11:44 AM

If you figure it out to be something other than the electric fan itself that is causing problems, you can always just go the ghetto way and put a switch inside the car. Wire the switch to the fan. Any time you run your a/c or whenever you notice your temp gauge coming up, hit the switch to activate the fan.



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Posted 30 June 2013 - 08:16 PM

Thanks so much everyone for your responses! Now I have a couple things I need to try. I wont have time all this week unfortunately to mess with it but I'll keep you posted and likely ask more questions later! and yes, this is the turbo version.

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