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1973 Volvo 1800ES custom installation

jeslrs on Thu August 21, 2008 3:36 PM User is offlineView users profile

Year: 1973
Make: Volvo
Model: 1800ES
Engine Size: 2170 cc
Refrigerant Type: R132a

My problem is, when I run my ac in HOT Tucson, my engine overheats. It has been suggested that my condenser is of the old style and should be upgraded. THe current condenser is 20 inches wide and 10 1/4 inches tall. The condenser mounts in front of the radiator and covers the entire surface of the radiator. It was suggested that the air passing through the condenser becomes so hot there is little to no cooling being performed in the radiator.

Are the new style aluminum condensers able to cool the freon without superheating the air passing through?

Can I reduce the condenser size to 10 inches wide and 10 1/4 inches high and still provide enough cooling to the freon? This would allow half the flow of air to hit the radiator first.

Can AAC make such a condenser for me?


Dick-1973 Volvo ES

mk378 on Thu August 21, 2008 4:55 PM User is offline

Your condenser is just doing its job dumping the heat removed from the cabin. If it didn't do that you wouldn't stay cool inside the car.

This really means that your radiator or other parts of the engine cooling system are no longer up to the task. Check for blockages in the water passages or dirt or missing fins on the air side. If it happens mostly in traffic you might be able to improve things with a new fan clutch or adding electric fans.

jeslrs on Thu August 21, 2008 5:26 PM User is offlineView users profile

That's what I was afraid of. If I put a "modern" condenser that was smaller than the part in my car now, would that dissipate the heat. I was thinking that a modern condenser half the size of the unit in the car now that covers the entire surface of the car radiator. If I could get some 'cold' air to the radiator it would help. I run a thermostatically controlled fan. My engine fan was removed. This helped considerably. I use to overheat at my first traffic light stop. Now it takes two traffic lights to make me overheat. Hmmm. I am also installing Evans waterless coolant. I ordered that today.

Dick-1973 Volvo ES

bohica2xo on Thu August 21, 2008 6:50 PM User is offline

Hopefully you still have the OEM fan & fan shroud for that car.

The only thing wrong with your OEM fan was a worn out fan clutch. Removing it was not a repair.

Volvo used the same fan clutch on much larger cars without an issue. All you really needed was a new fan clutch. If you wanted to cool that car with an electric fan, you would need to upgrade the alternator to handle the 40 amps a proper fan will need.

Your system worked just fine with the OEM fan for years. It can continue to do so if you still have the original parts.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

94RX-7 on Fri August 22, 2008 7:50 PM User is offline

A newer, more modern condenser will allow MORE heat to be removed from the refrigerant and dumped into the radiator. As previously stated, you more than likely have an airflow issue.

jeslrs on Sat August 23, 2008 10:43 AM User is offlineView users profile

Yes, I "upgraded" my alternator and installed a larger battery when I installed my electric fan. I did the fan conversion because the electric fan moves more air. It also is a cleaner installation. I still have my original equipment fan and shroud should I ever be convinced to return to that setup. My engine ran considerably cooler after I installed the electric fan. The fan clutch was new within a year as that was one of the early attempts to cool my engine with the ac on.

Short of doing major body work, I am not sure exactly how I can improve the air flow into my radiator. I DO think you are right in your assessment. A very astute statement. I was thinking that if I installed a high efficiency condenser that was smaller, it would allow at least some of the air flow to enter the radiator without first going through the condenser.

For the air flow I am contemplating hood louvers towards the back edge of the panel to allow additional air to escape from the engine compartment. As it is now, the air flows down and out, under the car. My second idea was to add an air scoop on the sheet metal under the front bumper and ducting the scoop to the bottom edge of the condenser/radiator. I am also in the process of removing and relocating the car horns as from the factory back in 1973, they were placed just right to cause an excess of turbulation in the air flow. My chrome grill surround has a lip to attach the plastic grill insert. This lip is 1/2 inch high and surrounds the entire opening. This also, I would think, causes a good deal of air turbulance and obstruction. As you look into the radiator from the front, the sheet metal is formed with a "rise", and then dip to the bottom of the radiator. This would cause an obstruction to the air flow I would think. To fix these problems would require major body reconstruction so obviously, I would want to be sure before I performed these modifications.

But we do agree on one thing. Air flow is the problem, for sure. I'd like to start by opening at least a portion of the radiator to cooler air by installing a shorter condenser. 20 inches wide by 8 inches high would be a start. My current condenser measures 20X14 and covers the entire front surface of the radiator.

Thank you both for your input.

Dick-1973 Volvo ES

94RX-7 on Sat August 23, 2008 4:47 PM User is offline

How old is your radiator? Has it ever been sent to the radiator shop to have all of the corrosion rodded out of it?

Under what conditions does the car overheat? On the highway or in town in stop and go traffic? If it is doing it in stop and go traffic only, then you need a fan that can move more CFMs. The little airflow tweaks that you're talking about probably won't make any appreciable difference at highway speeds and will make no difference in town in stop and go driving where you're at the mercy of the fan.

mk378 on Sat August 23, 2008 4:58 PM User is offline

I agree with the radiator part. If it's a replacement radiator is it some kind of knock-off that doesn't have OE performance? Go over the entire cooling system. Overheating with the A/C on means you are right on the verge of not being able to keep the engine cool with it off. I also strongly agree with what Bohica suggests about putting the stock fan back on.

A smaller condenser is not the answer. Assuming it doesn't reduce your A/C performance, that means it will still be putting exactly the same number of BTU's into the airstream entering the radiator. Even if part of it is bypass cool air, the part that is not bypassed must then be proportionally hotter. You basically gain nothing.

jeslrs on Sat August 23, 2008 8:48 PM User is offlineView users profile

My radiator is less than two years old, is an NOS product from Sweden. I had my car in being tuned on the dyno and they could not keep it cool at all. Pulled the radiator and had it rodded and acid cleaned. Improved from some 10% flow to nearly 100% flow. So much for holding out for new stock. They were able to finish the dyno run without a problem. However, my engine still overheats with the ac on, and I'm idling in traffic. My stock fan has a new clutch. My electric fan moves far more air at the critical low speeds than the stock fan. The electric fan, unless someone has some clear, hard data, is the best fan for the job. The fan alone accounted for nearly 50 fewer overheats in traffic. The car never overheats when cruising at highway speeds.

What you all are saying is, changing condensers will make no difference. I will be installing Evans coolant next week. They will flush my engine completely before adding the coolant. That should help considerably.

My engine was never intended to carry the load of an air conditioner. It was an aftermarket product installed only at the dealer. I can see why they never ac'ed the engine at the factory. I am also thinking of ducting the air coming into the radiator, much like you would do on a race car. Air flow is the key, I'm sure of that. From what you all are saying, you also agree.

This is my only problem with the car other than a rough idle due to an over exuberant cam grind... :-) Other than that. it's a fun car to drive. I've owned it since 1991 and wouldn't sell it for any price. It just turned 100K Miles so the car is officially broken in.

Thanks for all the good help, guys. Everything you have mentioned has been documented into my record book for future consideration. I only make one change at a time so that I can evaluate the progress from that change. Coolant is next.

Talk soon,

Dick-1973 Volvo ES

bohica2xo on Sat August 23, 2008 10:21 PM User is offline

Don't know what to tell you. A close friend put over 300k on a P1800 with a York compressor and a tube & fin condensor without a heating issue. Must have been the mild Las Vegas climate.

You might want to collect some data on the discharge air temperature from the heat exchanger stack. A T/C in the airstream on a stock 2005 vehicle will see 155f before the fan clutch locks up.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

TRB on Sat August 23, 2008 10:43 PM User is offlineView users profile

On average you increase the operating temperature about 15 degrees when running a properly working factory or aftermarket system. My opinion, if your cooling system can't handle a 15 degree increase in temp load. You have issues with the cooling system.


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