Hi everyone. I’m getting geared up to convert the AC in my 1991 240 from R12 to R134a. I have a fairly new (less than a year old) but used Sanden compressor (PN: U-4627) and the Volvo retrofit kit (PN: 9145666). If you don’t mind, I’d like some of you to chime in and let me know whether or not I understand the process correctly. I’m just gonna run through it generally just to keep it as short as possible and ask a few questions at the end.

What I’ve done so far is:

1. Had the R12 refrigerant properly evacuated from the system by a licensed tech.

What I need to do:

1. Remove old R12 compressor, receiver drier and orifice tube.
2. Install replacement compressor and AC conversion kit per instructions.
3. Take car to a licensed tech to have the system evacuated/flushed for recommended amount of time or at least 50 minutes to an hour.
4. Fill compressor only, with proper amount of ester oil through filler plug on top of the compressor. No oil should be placed in the reciever drier.
5. Return car to the tech to perform a vacuum test to be sure the system is properly sealed.
6. If vacuum test is successful, fill system with the recommended amount of R134a refrigerant.

These are my questions:

1. Are my steps in order; specifically evacuating/flushing first, filling the compressor with ester oil second and then doing the vacuum test?
2. Since I don’t have gauges, does anyone know how many cans of R134a I should put in the system? The Volvo Club page starts with the 740 system and doesn't address the 240.
3. Is there a recommended brand of refrigerant that I should use when filling my system or will the Johnsen’s that Wal-Mart carries be sufficient?
4. When filling the system with refrigerant, should I only hold the can upright or should I rock it back and forth? Or, should I sit the can in a bucket of warm/hot water or any combination thereof? I’m told that sitting the can in warm/hot water can help keep the refrigerant from getting too cold allowing the system take it in as a gas and not a liquid.

Okay, I have these instructions from the UK Volvo Club page that seems to do a good job of explaining everything.

http://www.volvoclub.org.uk/faq/VolvoR134Conversion/R134ConversionPage1.htm.

If any of you have any advice or suggestions, I would greatly appreciate it, so please let me know what you think. Wish me luck and I look forward to a nice cool Brickmobile!

Jason

 

Hello again. I know it’s been over a month since I posted on this topic, but I’ve been going back and forth with this AC. I recently found out through a UV die test that I had a massive leak from the AC discharge hose on my car. I replaced that today and understand that I should now pull a vacuum on the system to remove any moisture and outside air from the line since I had it open. Well, the thing I can’t figure out is now that I have replaced the compressor, I no longer have a “high side” pressure port to access on the rear of the compressor. So, is there some other way to pull a vacuum on the high side or will pulling it from the low side be sufficient? I don’t think so, but I’m not sure. I’d appreciate any help. Thanks everybody.

 

I have successfully charged my 740 pulling a vacuum from only the low side. Purpose of pulling vacuum is twofold: To remove air and moisture from the system and to draw in the initial refrigerant charge and raise the pressure to a point to where the low pressure switch allows the compressor to turn on. If the system is just empty (atmospheric pressure) but not under a vacuum, you will not have much luck trying to charge it.

If you had a massive leak and the system was basically empty for awhile, I would recommend replacing the accumulator or receiver-drier as the dessicant is most likely saturated. (budget 40 bucks).

One other thing - the "recommended" amount of refrigerant when doing a conversion to 134A from R12 is to use only 80% of the R12 amount.

Good luck with it..

 

wow that sounds like a really expensive and entailed not necessary process...I would 1. Put new seals on the A/C hoses. 2. Go to Napa,Oreilly's,Auto Zone, whatever you have in your area and buy a R134 retrofit kit. Buy 2 extra cans of R134 just in case. Also buy a can of the oil. All the instructions are in the box. Put the new R134 fitting on the Low pressure A/C hose and fill a can of oil first. Then follow by filling the R134. Replacing the drier may be a good idea but I do not find it necessary to replace your A/C compressor if it's working...I have retrofitted dozens of 240's without evacuating etc. Cause most of them leak so bad they have no R12 left in them...hope this helps

 

Quote:

Originally Posted by Joseph/TX

I have successfully charged my 740 pulling a vacuum from only the low side.

Thanks, Joseph/TX. The fact that you have pulled a vacuum from the low side only is encouraging. I’ll work with that tonight. I did in fact replace my drier since I used the Volvo retrofit kit. Its installation was straight forward. Replacing the discharge hose was simple too. I purchased a set of gauges today and already have a pump. I’ll attempt to pull the vacuum tonight and post back with the results.

Quote:

Originally Posted by Joseph/TX

One other thing - the "recommended" amount of refrigerant when doing a conversion to 134A from R12 is to use only 80% of the R12 amount.

I have also heard that it’s recommended that you only use about 80% of R134a when charging. Will the gauge give me a reading to let me know when I get to the right amount? This will be my first time using them, so I’m not quite sure what to look for. I was told that two 16 oz cans of refrigerant should be enough. What do you think?

 

I was able to pull a vacuum from the low side port on the U pipe near the drier. I ran the pump for 30 minutes and allowed it to sit for about 15. Eureka! My low side needle never moved. That told me I had no leaks. I then charged the system with two 12 oz cans of the R134a refrigerant, and I have good cooling. What I’d like to know is, with the low side gauge only hooked up, where should my needle be to indicate that I have a proper charge?

 

You did use a can of R134 oil too when you charged the system correct? I hope you did because the compressor could bind up if it's too dry...I had one bind up on me once when I did not use oil, not cool... I beleive the system holds 2.4 lbs of freon...make sure it's just not in the red or warning area...believe high green to slight blue is ok...but you don't want to overpressurize the sytem and cause something to blow or break...did you repklace your condensor too or just compressor and drier? A lot of leasks come from the A/C condensor(part in front of your radiator..)

 

Yes, I poured 6.4 oz of ester oil directly into the compressor per the instructions I read on the Volvo Club page. The oil came with the retrofit kit that I purchased from FCP Groton.

http://www.volvoclub.org.uk/faq/VolvoR134Conversion/R134ConversionPage1.htm.

I also read 2.4 lbs is the proper charge which I think translates to roughly 38 oz of refrigerant (I’m no mathematician but I think that’s about right). The cans I use are 12 oz cans so I’m short about 1 can which I’ll probably put in tonight.

No I did not replace the condenser, just the compressor and drier. I was working with a bit of a budget which is why I decided to do it myself, so I decided not to touch the condenser although I believe it would have been a good thing to do. After vacuuming the system however, the vacuum held for 15 minutes, so I’m confident there are at least no leaks. I figure I’ll take the pressure washer to the condenser one weekend to at least knock away as much dust as I can to help it breath better. Now that I’ve had this practice, if the opportunity presents itself to do the condenser, I will in the future.

Does anyone know of a relatively easy way to fix the recirculation flap? I really don’t think mine is working as I don’t hear anything when I hit the button nor do I notice a temperature change. Do I have to remove the dash? Any thoughts?

 

All the vents are on a "vaccuum" system. If your recirc is not working it's not the flap it's either a bad switch or most likely a bad vacuum hose,a bad diaphragm or a disconnected hose somewhere. First you are going to have to remove the center console and look at the back of the recirc switch see if the vaccum hose is connected and not broken. Then follow that hose and see which diapragm it is connected to. The diaphragm opens and closes the vents. Also,make sure that the vacuum hose under your hood on top of the intake manifold of the motor is not cracked, disconnected or leaking.Hope this helps.