134a

[OrangeAirsoft]

I have a couple questions for you regarding your A/C.

First of all, the 1986 Volvos came with A/C systems that use R-12 refrigerant. Has your system been converted to R-134a? If not, I wouldn't suggest mixing the two types of refrigerant.

Next, do you have pressure gauges to measure the pressures on both the high and low sides of the system while it is operating? I wouldn't try to add any refrigerant unless I know the internal pressures. Besides, the measured pressures will tell you instantly whether or not the system is fully charged.

Now for the strangest question of all, can you still change the direction of output air flow between the defroster vents, dashboard vents and under dash vents using the dashboard slide control? Likewise, will the heater still blast out very hot air when your temperatue control is slide all the way to the right? This is an important thing to check. Your vent and temperature controls are activated using engine manifold vacuum. There is a vacuum reservoir tank under the front end of your car, which is positioned in front of the front crossmember between the front tires. The precarious position of this tank makes it an easy victim of damage from running over road debris. If this reservoir has been damaged and no longer holds vacuum, your vents will default to the defroster mode and no air will blow from the dashboard vents. Likewise, the temperature control valve will not open and you will no longer be able to heat the interior of the car on a cold day. A vacuum leak such as this can also effect the turbo boost in turbo equipped cars. Take a look at this before you go any farther.

Keep us posted as to what you find. I like to hear success stories.

Hi. Thanks for the clarifications. The big silver tank looking thing (dunno what's it called) has a blue sticker saying "retrofitted for HFC-134a", so I don't believe the system uses CFC-12.

I only have guages for the low side (blue cap?) and it shows less than 5psi when the A/C on. But drops to 0 with the engine off. What happens is when I add refrigerant, the guage would climb to about 10psi, and keep dropping. I don't believe the refrigerant is ever leaving the can. The can does get cold though. I realized that the compressor isn't cycling at all. When I short the sensor pins, the compressor start working. But if it is attached to the sensor, it wouldn't turn on. Sensor failure?

Changing between vents work w/o problems, you can actually hear the swiiishhh when changing from say face to feet to windshield hehehe... I did not know it was operated by engine vaccum, and wondered by it made swish sounds when changing vents... Heater works perfect too.

Kinda stuck here, and I don't wanna bring it to volvo service yet. They charge me $$$ everytime I go there.

[AMcK]

Is your can pierced all the way? did you back the piercer off after you pierced it? you should get the leak fixed first, and after the leak is fixed the system will have to be vacuum pumped to get the moisture out.

[Kmaniac in California USA]

Well, now I know that your car has been converted to R-134a and your vents are working perfectly. The low low-side pressure reading indicates a lack of refrigerant in the system. The sensor you refer to in the A/C system is a pressure interlock. It prevents operation of the compressor when refrigerant is low. It is working as designed and another indication of lost refrigerant.

When you add refrigerant to the low-side, you need to have the engine running, with the compressor on. You need to bypass the sensor to do this. When filling the system, it is best to run the engine at 1500-2000 rpm. Once you puncture the can, you need to open the valve back up all the way. Your can will form a reservoir of refrigerant, with gas on top and liquid on the bottom. When you hold the can upright (top up) the system will draw in gas from the can. When you hold it upside down (bottom up) it will draw in liquid. The can will turn cold as refrigerant is drawn into the system. It can take a few minutes to fully dispense the can. Be patient. By shaking the can, you can tell whether or not there is liquid refrigerant left inside. Disconnect the can when you shake it and it feels empty.

These systems can take up to three 14oz. cans to fill from zero. I would recommend getting a high-side pressure gauge to make sure you don't over pressurize the system.

Now, if you add a can, and don't see any change in the system pressures, you most likely have a leak that needs to be repaired.

I hope this helps.