I've read several posts about AC performance on the old 240 vehicles. I'd like to offer a few suggestions that might help those with systems that can't quite keep up.

Model Year Changes

The 240s sold in the North American market up through model year 1990 had an old-styled expansion device to meter refrigerant. Those systems also had been sized for a climate of Sweden or somewhere like Toronto Canada. As those cars became popular in the US and traveled to the Southern states, the climate was hot enough for them to inadequate. On an 85 degree day with moderate humidity, it was fine. Give it a 98 degree day in Birmingham AL, Atlanta GA or Orlando FL and it could not keep up.

Volvo recognized the deficiency and changed the AC system for 1991. It was basically a GM evaporator, accumulator and orifice tube grafted into their existing refrigeration circuit. The compressor cycled based upon the low side pressure and the cooling capacity was greatly enhanced. For 1993 the system was changed to R134a refrigerant and a booster fan was added to the condenser to make up the R134a's efficiency gap on cooling. Those 1991 to 1993 systems worked quite well. I had many of them and they had no problems cooling in a hot climate.

Improving Efficiency

Short of tearing apart the dash and underhood areas, swapping lines, rewiring and other fun things, retrofitting a 1990 and earlier 240 for the later components is not easy. For most people, it will never be worth the engineering effort so I am going to offer a few suggestions that might help.

Keeping in mind that the 1990 and earlier system is undersized for a hot climate, the following list of improvements will help. At this point, all that you can do is try and reduce the heat load and improve the efficiency of the existing system.

• Add professional window tint to reduce the solar load on the interior, keeping in mind whatever your local laws are regarding tint. Don't inhibit your vision with the tint job.
• Examine the space between the fan shroud and radiator, radiator and condenser, filling those gaps with some type of seal. I've used foam weatherstrip in the past for older GM cars that were originally R12. The idea here is that you are going to pull more air across the condenser by making it impossible for the air to go around the condenser. You can get what I would estimate a 10% improvement in airflow by doing this. One easy gap filler is that soft foam pipe insulation that can be tucked in a joint and appear OEM. Make sure that it is secure because you don't want the fan sucking the insulation in as you drive!
• Replace the fan clutch with an OEM unit or one from Hayden or similar suppliers. In other words, put out the cash for a decent fan clutch that has a thermal coil on the outside.
• Remove the radiator and backwash water through all of the fins. Do the same thing with the condenser. I've seen cars where the bottom 1/3 of the condenser is full of leaves and dirt. No airflow is going across that section of the condenser. Wash it through and clean it as much as possible.

As you drive, the airflow goes across the condenser just fine due to air pressure. But, at idle, here is where the foam seals and better fan clutch will shine.

 

I would also suggest adding a "pusher" type electric fan (Hayden makes them too) to the front of the condenser and wire a relay into the + 12V of the receiver/dryer low pressure switch. This will turn the fan on as soon as you turn the AC switch on.

 

Thanks, Tony That's all good advice. I can also suggest the so-called Tropical fan clutch ( part number 1357433) It is a heavy duty model (made by Aisin) that will pull more air for A/C and cooling purposes for 240 and 740 models. In addition, using the re-circulation button pushed in will help to keep the hot outside air out of the car.

 

I like the part number for the tropical fan. That's a beefy looking unit.

https://www.ebay.com/itm/Engine-Cool...sid=m570.l1313

Regarding the pusher fan, yes, it is an addition that will help. I tried to keep my suggestions to what I perceived as the average DIY and didn't want to send them on a job that they might not handle. The other issue is that the pusher fan will run continuously unless you wire in an on/off switch. While driving, there is enough airflow to eliminate the need for the fan. The fan would be a constant power draw otherwise.

 

All good info! Thanks everyone.

 

On my 89 740 it came with a pusher fan. It was wired to s thermo switch in the radiator. I added a relay and ran parallel wires to it. The relay was triggered from the low pressure switch on the receiver/dryer (hot wire). The orig. intent of the aux. fan was to turn on when rad. switch triggered. That still works but with my set up when you turn on the AC the fan comes on and when you turn off the AC it shuts off. I could have also tapped the compressor to trigger it but this worked out just as well.

 

I saw a YouTube video where a 740/940 puller fan was sourced from a wrecking yard, along with the wiring harness and other accessories and fit to a 240. Basically they eliminated the engine fan and shroud, using the later electric fan.

There's a lot of engineering that went into that one since you have to have a control for the cooling fan regarding engine temperature and also the AC system. There weren't a lot of details in the video but there's an answer for someone who wants to take their 240 to the next level.

 

note the 92+ 7/940's have a larger 2-speed electric fan and radiator, these had no engine mechanical fan at all.

 

Yes, that's why I mentioned it in the above. It seems that he figured out how to incorporate that system into the 240. As far as running the fan full time when the compressor is engaged, most of the driving wouldn't need the fan, only at idle while sitting still. The newer models addressed this by having a pressure sensor in the high side of the system to run the fan when the pressures built up.

Years ago on a Volkswagen diesel that I had, the system worked by running the fan the whole time that the AC was on. It was a two speed system, I had a mechanic wire up an on/off switch with two indicator lights telling me if the system was calling for first speed fan or second speed fan. When I was traveling down the road, I turned the fan off.

 

pretty sure (albeit not positive) that my 92 740 ran the fan on low if the engine was on, and high if the AC was on OR the engine was hot. there's a 2 speed relay near the fan used to control it.

 

Back in the day I sold a lot of those cars and noticed that the system engaged the cooling fan when the pressure built up. For most purposes, the fan ran at low speed when idling unless the engine heated up or the pressures got higher.

I think that the cut-in point on the fan was 180lbs on the high pressure side. I ended up servicing a lot of those systems since many needed either recharging or repairs. I used to do 10x the AC work that I do now. How things have changed.