I have begun having problems with my 87 xj 4.0 auto lately this summer. My temp spikes at random intervals, though I can force it up by runnign the A/C while stopped. I have had to run the heater a couple of times to bring it back down. Am I looking at a thermostat or radiator prob? In addition to this, I am on my FOURTH cooland reservoir. They have all become bloated to the point of rupturing, and the one I have now is gonna go any day now.

Also, for anybody good with A/C systems, I cannot get my A/C to blow out the front vents for the life of me. It all blows out the defroster vents in the dash. What do I need to think about here to correct the problem. Here in San Antonio, we have had a record summer of 100+ degree weather (on day 40 or so now). Needless to say-its been a little uncomfortable lately in the cab of the jeep.

Any and all help is greatly appreciated.

 

i used to have a chevy truck that ran hot during the summer time here in the south and i know that i would just run the truck without a thermostat and i would never have a problem since your in "warm" climate haha this might work for you also as for the air vents they change using vaccuum dont know if you have checked that yet

 

Sounds like a vacuum leak problem with the A/C vents. Not sure about the 87 but later models had a plastic vacuum reservoir behind the front bumper on passenger side, they are prone to crack and leak.

 

Probably a clogged rad. Does your electric fan work and does it turn fast?
You can manually switch the flaps that rederect to the front vents by unhooking the levers from the vacuum motor (under the dash pass side) that probably don't get anymore vacuum supply.

 

i was kinda thinking clogged radiator too...is it packed with mud by any chance, are all the little coils still in the radiator?.....

on the YJ i just sold, the radiator was missing half of its coils, and the coils that remained were clogged with mud...lol.......so it was a bad one....i couldnt drive it more then 5 miles on the highway before the gauge was all the way in the red as far as it would go......

but try just buying a new radiator cap first.....maybe your old one isnt getting a good seal.....if that doesnt work, get a lower temp thermostat, or even try running it without for a while....if those fail, then its probably time for a new radiator.....

but like i said, if its clogged and or half the coils are missing, then that would most likely be the problem....but its always best to start with the cheapest/easiest solution first and work from there....i.e. the radiator cap