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Topic: 88 T/C Overheating only with A/C (Read 4727 times) previous topic - next topic

88 T/C Overheating only with A/C

The car 88 T/C built 302 S/C 5spd 470 rwhp, the issue overheats only with A/C on at highway speeds.At steady 2K rpm it starts to creep in temp from 170 up to 210,that's when I turn off the a/c and starts coasting to cool it back down. Without a/c on you can drive all day long without issues. even city driving with a/c on it seems ok. 

160 hi flow t-stat runs at 170ish w/o a/c on
Mishimoto rad new
Flow Kooler hi flow w/pump
Boxed the rad in for more air
50/50 mix
V6 Contour elec/fans
Mach 1 chin spoiler
New condenser


The solution  ?????????????? Thank you.

88 T/C Overheating only with A/C

Reply #1
AC hi and lo side pressures?  What is your CAC setup with the blower, is it air to air, air to water, closed, none, and where are the heat exchangers if indeed you are using any kind of CAC? Is there any kind of debris or blockage between the condenser and radiator? Also, I'd like to remind that whatever your t-stat temp is, 210 is considered to be normal.  You say you have a Mach I chin spoiler, pics? A lot of TC guys here have cooling problems because of missing/damaged air dams.  Since you've got electric fans, do they (or at least 1) run when the compressor clutch is engaged?

88 T/C Overheating only with A/C

Reply #2
Not sure what the a/c pressure is at hi or lo side or what it should be or how it affects my water temp?Vortech no intercooler, rad and condenser are new and free of derbies, my fans are always on. The chin spoiler is from late model restorations the cheapest one they sell its about 3-4 inches longer on each side just cut those ends off, and i had to notch the corners on the inside of the chin spoiler to follow the birds tighter radius at each corner. When i take some pics ill try and post.

88 T/C Overheating only with A/C

Reply #3
The higher the hi side pressure, the hotter the condenser will be, and the hotter the condenser, the lower the air quality is when it flows over the radiator. The next thing is to verify coolant flow.  At the shop we have a tool for this, but I don't know how to tell you to check it.  What does it mean "boxed the radiator in"?

I'd really wish I could watch your AC pressures.  I think that would tell the whole story, because the difference between ac on and ac off as it relates to cooling system performance is going to be the temperature of the condenser.

88 T/C Overheating only with A/C

Reply #4
Here is a properly working system in 90*- 95* weather at 1100 RPM





Sounds like your radiator is clogged or to small. Or not enough air across it!!
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

88 T/C Overheating only with A/C

Reply #5
Tom is the hi lo pressures based on how much freon is in the system or will the pressure rise if the condenser temp are not properly managed ? The rads new with very low miles on it, I would lean towards to small or my contour fans are tired,not sure the water pump is a flow kooler which is suppose to increase flow by a bunch.

thanks


88 T/C Overheating only with A/C

Reply #7
Angry i posted the mach chin spoiler pics in body and appearance section

88 T/C Overheating only with A/C

Reply #8
AC pressures are a combination of Outside temps system charge to an extent and how much air and the size of the condenser

In the body shop The insurance companies sometimes require aftermarket parts. This can be tricky as we replaced a condenser in a Toyota and an aftermarket unit was used. IT DID NO WORK. I ordered one from the dealer with vin verification and the system worked perfectly. It takes years to learn AC as every system is different and even different in the same cars. But you need to see what your pressures are and you need a pressure temp chart to verify operation. Thanks

A couple of questions

1 how big is the radiator.
2 what kind of fans and how big?
3 do you have a stat and what is the temp of the stat.
4 does the radiator have good air flow at high speeds?

You may be over cooling just a thought!!!
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

88 T/C Overheating only with A/C

Reply #9
T stat 160 hi flow
rad is a stock size 2" thick 2 core aluminum
fans are from a v6 contour I think there twin 11" they seem to pull a lot of air to keep it at 170-180 without the air on at highway speeds

88 T/C Overheating only with A/C

Reply #10
Well the water cools the engine and the radiator cools the water. With tha AC on this process is not working??? Just a thought if you slow down the water flow through the radiator with a regular stat at 180* this might allow the water to stay in the radiator longe and cool better. Normally at highway speeds there is plenty of air across the radiator so the fans are a wash??  (i think) Try replacing the stat with a higher one and go from there. You need restriction in the system to allow the coolant to stay in the radiator long enough to be cooled. You just may have over cooling ??? Also does the car have the lower valance installed??? It needs this to direct air flow through the radiator. Remember the TC nose is completely closed off to air flow.
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!


88 T/C Overheating only with A/C

Reply #12
Yes it has a Mach 1 chin spoiler ,not sure where i read it i think it was a water pump company site stating that by slowing down water flow to keep it in the rad longer also keeps it in your hot motor longer having a negative effect on cooling. i think i'm leaning towards a larger better rad but not before having the A/C pressures checked as the car is fine at highway speeds regardless of temp. Or get new fans to draw more air with ac on not sure anymore.

88 T/C Overheating only with A/C

Reply #13
Quote
TOM Renzo
Normally at highway speeds there is plenty of air across the radiator so the fans are a wash?? (i think)


I would agree with Tom on this. If the fans are enough in stop and go traffic, I would find it hard to believe they are the problem at highway speeds.

88 T/C Overheating only with A/C

Reply #14
Except that you shouldn't be running fans at highway speeds. When under fan cooling at a stop, you have much lower thermal load to deal with.  At highway speed, you have sufficient high pressure in front of the cooling equipment as to overcome the equipment's ability to allow air to flow through. You're flowing as much air as can be allowed by the condenser's design, and you can only flow as much air through the radiator core as you can get through the condenser core first. A spinning fan under those conditions can reduce your potential airflow, since the capability of the fan is lower than the raw capability of the condenser core.  Your fans should be depowered so that the blades are just along for the ride.