88 EA82T Posted June 15, 2009 Share Posted June 15, 2009 I have a 1988 GL10 fulltime 4WD 5MT turbo wagon. The water temperature is normal all time except if I turn the AC on. When I turn the AC on I can watch the temperature go up and then I turn it off before it gets to the red and it goes back down to normal pretty quick. This happens even at 70 mph where there should be plenty of air moving across the radiator. The car got a new radiator/thermostat about 2 years ago but then the car sat for 18 months while I was over seas. Oh, the radiator is full of coolant too. I am thinking of starting with draining/refilling and putting in an OEM thermostat, is there something else to look at? Link to comment Share on other sites More sharing options...
Caramanos2000 Posted June 15, 2009 Share Posted June 15, 2009 You should never let it get to the red. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted June 15, 2009 Share Posted June 15, 2009 Replace your radiator and flush the system. It's not rejecting enough heat and it's being saturated by the AC evaporator core. GD Link to comment Share on other sites More sharing options...
88 EA82T Posted June 15, 2009 Author Share Posted June 15, 2009 Replace your radiator and flush the system. It's not rejecting enough heat and it's being saturated by the AC evaporator core. GD Even though the radiator is only 2 years old? You should never let it get to the red. I haven't let it get to the red. Link to comment Share on other sites More sharing options...
TRAVIS75 Posted June 15, 2009 Share Posted June 15, 2009 This is a shot in the dark, but my 89 5spd m/t had a similar problem except mine did it randomly when I turned on any accessory temp gauge would spike. Or if I hit bumps, which finally clued me in that it wasn't really running hot. After searching and searching finally found that when I had swapped engines, the auxilary ground wire I'd hooked back up had come loose. Tightened it back down and voila...problem gone. Hopefully it can be this simple for you. Link to comment Share on other sites More sharing options...
88 EA82T Posted June 15, 2009 Author Share Posted June 15, 2009 So at break time, I started it up and watched the AC compressor belt. When the compressor turns on, there is definitely a load on the system and the belt starts to jump at bit. The jump smooths out when the AC is turned off. The belt tension ok and the electric fan is turning on. So I am guessing the AC compressor is putting too much drag on the system and it makes the engine run hotter. Is there a cheap way to fix this (other than roll down the window...)? Link to comment Share on other sites More sharing options...
Caramanos2000 Posted June 15, 2009 Share Posted June 15, 2009 Increased drag shouldnt increase temperature I dont think at least. It just means your engine need to run at slighlty higher rpms to spin the belt at the same speed. And if it still does it while driving at speed I would think it has nothing to do with increased drag. I could be wrong though Link to comment Share on other sites More sharing options...
85T-REX Posted June 16, 2009 Share Posted June 16, 2009 Where does your gauge read when it's "normal"? My gauge reads 3/4 at normal. When I use the AC it goes up to the red which is actually 195 degrees which is normal while the AC is running. My gauge is off and yours may be as well. Take a meat style thermometer and tuck it in along the rad against the upper hose on the pass side and see what it says. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted June 16, 2009 Share Posted June 16, 2009 One of a couple things is happening - your radiator doesn't have enough flow, your head gaskets are leaking, the cooling system has air bubbles in it, or has leaks and can't get up to pressure. The AC was designed to run with on the hottest day with the engine only idleing. Something isn't right with the coolin system - fix it right or pay the eventual consequences of destroying that engine. GD Link to comment Share on other sites More sharing options...
zukiru Posted June 16, 2009 Share Posted June 16, 2009 then don't run AC? sorry had too does the electric fan come on with the AC? do you still have the belt driven fan installed? yes a radiator can go bad sitting up for two years. Link to comment Share on other sites More sharing options...
TomRhere Posted June 16, 2009 Share Posted June 16, 2009 Make sure there isn't any debris between the radiator and the condenser unit. I've seen that a few times, especially on vehicles that have sat for awhile. Link to comment Share on other sites More sharing options...
88RxTuner Posted June 17, 2009 Share Posted June 17, 2009 (edited) +1 on checking for debris or clogging inside or in front of the radiator. Yes, 2 years on a radiator can DEFINITELY cause problems, especially if there are mineral deposits in the Radiator or Engine, or poor/ infrequent cooling system maintenance has been performed, such as sitting for 18 months... Just because the engine isn't running doesn't mean the chemical reactions that cause deposits and mineral sediment are not happening... When you run the A/C, it pressurizes the gas in the system. This makes LOTS of heat... That's what the condenser in front of the radiator is for. Now, lets take an average day. 80degrees outside, driving along, 80degree air going into the radiator. Just fine, even for a partially clogged radiator, to dissipate enough heat. Now, turn the A/C on... That condenser, which sits right IN FRONT of the radiator, gets up to about 150- 175 degrees, sometimes more. Now, you dont have 80 degree air going thru the radiator, you have 125-150 degree air going through there after heat transfer from the condenser. This will Drastically alter the heat transfer out of your radiator, and if it is not performing 100% it may not be able to give up heat fast enough. Look into the radiator. Have it checked out, Rodded, or Replaced. GeneralDisorder has a very good point when he says fix it right or pay the price... 200.00 for a radiator, or 2000.00 for an engine or head gasket job? Wont hurt to check into the gauge possibly being off, either.. My RX goes to the red at 205 degrees... Not very hot, but the gauge is off. It's fairly common. Hope this helps... 88RxTuner Edited June 17, 2009 by 88RxTuner Link to comment Share on other sites More sharing options...
88 EA82T Posted July 17, 2009 Author Share Posted July 17, 2009 The fan clutch was weak or the spring in it was broken. Replaced it with a used one from the junkyard and now the temperature stays closer to normal when the AC is on. Supposed to be close to 100 here tomorrow so we will see if solves the issue or not... Link to comment Share on other sites More sharing options...
Quidam Posted July 17, 2009 Share Posted July 17, 2009 Hi, "is there something else to look at?" If you didn't buy the best radiator you could lay your hands on, you messed up right there. Single core is a mistake in these cars. Sincerely, Doug Link to comment Share on other sites More sharing options...
88 EA82T Posted July 17, 2009 Author Share Posted July 17, 2009 swapped the plastic one for an all metal one that is for an automatic but i am not sure if it is single or dual row. the temperature is normal and rock solid all the time without the AC running. Link to comment Share on other sites More sharing options...
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