The above post is what I shared on the Volvo board. There are still a lot of 240 owners out there who do this dance every year, wondering how to get their car to cool down. Here's exactly what I posted on the Volvo board, unedited:
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.
