Another question for you A/C experts...

[90MarkVII]

I've been chasing a running too warm issue for a while.
1990 Lincoln Mark VII with a 347, a 4R70W and a 9 1/2 inch converter from Mike's Trick Shift. Very low stall, maybe 2800-3000. 11x9 transmission cooler attached to the condenser. It runs through the trans cooler then to the external.

I've gone from the stock fan to a Flex-a-lite extreme 185 back to a stock fan (so I could rev it or leave it in 1st and cool it down in traffic) to a Mark VIII fan with a Derale PWM controller.
Running down the highway (even in 100+ heat) all is well. Hit heavy traffic, it starts climbing. Stay in traffic and/or lots of stop lights it wants to get too warm. Kill the A/C the gauge starts dropping. Fast.

The compressor is the original with 230K miles on it. The system was converted to 134 by a shop in NRH several years ago. The A/C blows very cold in the cabin, cools it down fast, even in the current 100 degree temperatures. Stay in the car long enough and I'll need to drop it down to medium, maybe even low.

Is it possible that the compressor is so inefficient that it's generating too much heat? Or the condenser needs flushing?

Or do I need some twin turbofan setup that sucks small animals up to the grille?

All insight gladly accepted.

[90MarkVII]

For the record, the Mark VIII/PWM controller has significantly delayed the warm temps. And it comes down faster than before.

[Z06killinsbf]

What temps is it running? What t stat?

[BP]

Make sure the fins on your condenser aren't all bent up and it's not full of debris. More air flow across the radiator and condenser will probably help with the problem but the biggest fans in the world will still be sucking in 110+ degree ambient air when you are in traffic, a/c systems do have limitations.

[90MarkVII]

What temps is it running? What t stat?

I won't let it get past 230 before I turn off the A/C and it's a 195 degree T-stat.

[90MarkVII]

Make sure the fins on your condenser aren't all bent up and it's not full of debris. More air flow across the radiator and condenser will probably help with the problem but the biggest fans in the world will still be sucking in 110+ degree ambient air when you are in traffic, a/c systems do have limitations.

Air flow through the condenser is no problem.

[90MarkVII]

If the difference is only when the compressor is on, I really think that might be the culprit. Does it cycle on and off, or does the clutch stay continuously engaged?

The A/C system itself seems to be working OK. No unnecessary cycling, blows cold in the cabin.
It appears to be all about how hot the condenser is getting.

[svauto-erotic855]

The temp on the gauge is meaningless if you haven't confirmed that it is reading correctly. You are also not overheating no matter what the gauge says if you are not losing coolant.

On any car that has an aftermarket converter I do not use the factory cooler in the radiator at all. I instead get an fin and plate style heat exchanger and mount a small electric fan onto it and use a trans temp gauge. This tactic has been working for me perfectly for 25 years.

How old is your radiator? You may also want the verify your base timing and your timing marks as retarded ignition timing can also cause the issues that you are describing.

[90MarkVII]

The temp on the gauge is meaningless if you haven't confirmed that it is reading correctly. You are also not overheating no matter what the gauge says if you are not losing coolant.

On any car that has an aftermarket converter I do not use the factory cooler in the radiator at all. I instead get an fin and plate style heat exchanger and mount a small electric fan onto it and use a trans temp gauge. This tactic has been working for me perfectly for 25 years.

How old is your radiator? You may also want the verify your base timing and your timing marks as retarded ignition timing can also cause the issues that you are describing.

The radiator is new, although pretty thin due to needing room for the Mark VIII fan. A thicker Champion with the stock fan and then the Flex-a-lite was no better, though.

The timing marks are correct as I verified TDC with the mark while assembling the engine. And the timing is dead on 10 degrees.

I'm going to reroute the fluid to bypass the radiator, maybe that will help.

[Baron Von Crowder]

is it possible to get the car up to temp and check the condenser temperature?

I had a mustang that did the same thing, idling in stop and go would send the temps sky high with the a/c on. I found the alternator wasnt up to snuff, and the voltage from the fan was dragging it down to 10v, IIRC at idle. A 3g solved it.

[90MarkVII]

is it possible to get the car up to temp and check the condenser temperature?

I had a mustang that did the same thing, idling in stop and go would send the temps sky high with the a/c on. I found the alternator wasnt up to snuff, and the voltage from the fan was dragging it down to 10v, IIRC at idle. A 3g solved it.

Solid 3G is on it, fan is getting 12v when the PWM has it wide open.
It did the exact thing with the factory fan -with a Heavy Duty clutch for a F150- in it. Run around, all is cool. Slow down to a crawl, start warming up.

[Baron Von Crowder]

Time to get more air to it.

[svauto-erotic855]

What you are experiencing is a classic example of a cooling system that can not reject the heat as fast as heat is put into it. Can you describe exactly how the radiator is built? 1 core or 2 core? How big is each core? Is the top radiator hose or t-stat housing higher then the radiator cap? What is the part number for the water pump that you are using? Is it the correct one for your application? Who made it? Do you have under drive pulleys? Can you post a picture of the fan shroud? In some cases I can show you how to mod the shroud to get more air flow through the radiator. What is you water to coolant ratio? The max boiling point while not killing the coolants efficiency is reached at 60/40 coolant to water ratio.

You may want to consider adding a stack of washer between the hood and hood hinges enough to cause a very small gap between the back of the hood and the body to give the hot air a place to go. Doing that will solve your issues instantly.

[90MarkVII]

What you are experiencing is a classic example of a cooling system that can not reject the heat as fast as heat is put into it. Can you describe exactly how the radiator is built? 1 core or 2 core? How big is each core? Is the top radiator hose or t-stat housing higher then the radiator cap? What is the part number for the water pump that you are using? Is it the correct one for your application? Who made it? Do you have under drive pulleys? Can you post a picture of the fan shroud? In some cases I can show you how to mod the shroud to get more air flow through the radiator. What is you water to coolant ratio? The max boiling point while not killing the coolants efficiency is reached at 60/40 coolant to water ratio.

You may want to consider adding a stack of washer between the hood and hood hinges enough to cause a very small gap between the back of the hood and the body to give the hot air a place to go. Doing that will solve your issues instantly.

Thee radiator is unfortunately a cheap ass 1 row with aluminum tanks because there was not room to stuff the mark VIII fan between the 2 row all aluminum Champion that I bought last year because I thought more radiator wouls solve the issue. On the better radiator I ran the stock fan with a HD clutch from a F150. SAME RESULTS.
I had to go to a thinner radiator to run the Mark VIII fan.

I have the ratio somewhere around 70/30, or as best I could swag in a bucket and then using the specific gravity tester (new).

It is an Edelbrock water pump.
Moroso 195 degree t-stat
one bottle of HyperLube coolant additive.

Yesterday after I got home I bypassed the radiator, going straight to the 11x9 stacked plate cooler. In the past I've seen no more than 150 degrees on the transmission (watching the Baumann program on my laptop) so I'm not too worried the transmission will get too hot.
I'll let you guys know the results pretty soon.

Raising the back of the hood will be a last ditch effort.

Thanks for all the replies and help.

[svauto-erotic855]

Try switching to a 30/70 coolant to water mix with a little Redline water wetter.. It is cheap to do and it may take care of your problem.