1995 EXPLORER 4.O AUTO, A/C. 4WD, 4 DOOR

PROBLEM: CANNOT GET ENGINE TEMP TO 195 F.
I HAVE TRIED THREE NEW T/STATS-GATES MAKE.
195F EQUALS HALF WAY ON THE GAUGE, THIS WAS CONFIRMED BY AN INFARED THEMOMETER. AT HIGHWAY SPEEDS-100KPH.- SOME TIMES THE TEMP IS AT 195, THEN IT DROPS TO THE LOWER END OF THE OPERATING RANGE-INFARED READS 160F. TEMPS ARE READ AT THE THERMOSTAT HOUSING. SOME TIMES THE TEMP WILL STAY UP FOR AN HOUR OR MORE AND THEN IT DROPS LIKE A STONE AND RUNS COLD . WHEN IT IS UP I GET 26 MPG WHEN IT IS RUNNING AT 160 I GST 16 MPG.
HAS THERE BEEN ANY PROBLEMS WITH THE CLUTCH FANS ON
THESE MODELS?

THANKS FOR ANY HELP

 

Welcome to FTE!
This probably isn't what you want to hear, but the thermostat is the only thing that can cause that, IMHO. Try a different brand, Motorcraft or Stant. I don't think the clutch fan can make it overcool if the thermostat is working right and installed properly.

P.S. Please don't type in all caps. It looks like you're yelling.

 

I posted on this recently. I had problems with fluctuating temperatures that were generally in the lower half of the normal band. I founf that it was caused by a clogged heater core. I changed the t-stat and temperature sensors two times with no effect. Unclogging the heater core fixed the problem instantly. After you engine is running for a while, check both hoses from your heater core. They shoudl both be hot. If only one is hot, the core is clogged.

 

Wow, that's weird. How does that cause overcooling? Not saying you're wrong, I'm just interested.

 

here's how it was explained to me:
When the heater core is functioning properly, it exchanges coolant with the engine at all times. Thus, the heater core acts like a small radiator taking some heat away from the engine. This moderates the temperature in the engine so that the thermostat doesn't open as much or as often. Now, if the heater core is clogged, no coolant from the engine will circulate through it. As a result, the temperature will get to 195, the thermostat will open quickly, then the engine will get a full blast of cold water from the radiator, rapidly making the temperature gauge go down to the bottom of the range. This cycle will happen over and over again. In my truck, this happened in January, which was extremely cold in NJ this year, so the engine kept getting repeated blasts of cold. Before I fixed the problem, I put a piece of 1/4" plywood in front of my radiator. This kept the coolant in the radiator from getting so cold by blocking the airflow through it. The temperature still fluctuated, but generally stayed a little closer to the mid-point of normal.
As expected, my problem also caused me to have essentially no heat inside my truck since the heater core wasn't taking heat away from the engine to place it in my cabin. I froze my &*% off. I actually had ice on the inside of my windows while on a two hour drive.

 

Yep, that makes sense. Learn something new every day around here! I had the impression that DGGRAHAM's cycles were of very long duration, like the thermostat was sticking open.
Appreciate the info.

 

I agree it sounds like DGGRAHAM's temperature cycling is a longer duration. I just wanted to relay my experience since it was not obvious at all to me that a clogged heater core could cause my temperature to fluctuate. I suppose if there was chunks of sludge pumping through the coolant system, the heater core could become clogged intermittently, though I think that is not likely. Anyway, I think a coolant system flushing is in order since it is a rather cheap and easy thing to do.

 

just a thought, say if you turn off the heater and the valve on the heater hoses under the hood closes and allows no circulation through the core, then does this mean your engine will never warm up? if your answer is no, then a cloged core is not the problen. put a stant premium thermostas in for around 7.00 and be done with it.

 

Does the heater valve really turn off the flow through the heater core? I thought it just closed a vent door to prevent your cabin air from flowing past the heater core.

 

Hi Philip: The three stats I've used are stant premium. Stant is part of Gates. I'm going to replace this time with "Moto-Rad". It's the only other supplier other than ford. thanks for the suggestion.

HI Rob. Yes most cars today have a water shut off valve when equiped with a/c.
I'm going to change the stat this week end. Also it's brake job time-- 4 wheel disc including park shoes.

I'll let all of you know how the temperature is after the week end.

 

I'm wondering about when the blend door breaks. When that happens, you typically get hot air on normal A/C and cold air on max A/C. Does the air bypass the heater core altogether when it's on max or is that the only time the heater control valve closes?

 

I just put a stant premium in mine and fixed the prob, it had a 180 degree and i went back to the 195 and its working like a top.runs dead in the middle of guage.I also have a broke mixing door that i need to fix but doesnt affect the way it heats up.not sure whats going on with yours,dont take this the wrong way but, are you getting it in the right way? some people will put things back like they found them and might not always be the right way,specially if it was preowned and someone changed it before.good luck and i'll keep up with this thread and try to help you find the problem.

 

My blend door is fine, fixed it about a year ago. If you look at a lot of the posts about blend door breakage, lots of them blew warm on normal A/C and cold on max, as mine did before I fixed it. My question was about the functioning of the heater control valve, guess I didn't really state it clearly. Thanks for the reply, anyway.

 

open your glovebox all the way, push the sides inward and pull toward you.put the ac on and look in the upper right corner of firewall on the pass side and , while looking turn ac to max ac and watch door open. this draws inside air right to blower, with a flashlight you can see the fan cage.when on max , I'm guessing it bypasses the heater core.

 

I am having trouble. Maybe someone can helpme. I own a 1995 explorer, and I had great heat on Thurs., then Fri. all I had was cold air blowing. We changed the thermostat, that didnt help. Then we flushed the 2 hoses coming from the heater core, and I still have no warm air. Mine has the EATC instead of reg. heater, and i performed the self test and it didnt show any problems. I have also had it checked at AutoZone on the free diagnostic computer tester, and it showed nothing. Someone please help, i am anemic, and I freeze anyways!