Recharging A/C on '98 Mazda Protege...

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  #1  
Old 06-05-05, 08:06 AM
DanTheMan
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Recharging A/C on '98 Mazda Protege...

Hi guys, looking for a forum and found this one.

I'm recharging the refrigerant in the A/C on my dad's car. We had it discharged by a shop as one can no longer vent refrigerant into the air (this is r134a). I then replaced the clutch on the compressor but did not have to remove the compressor--only had to disconnect one of the lines to get to a certain screw. I'm now trying to charge it and all the lines are correctly hooked up, and the service manual says to charge it into the low side until the weight of the can has reduced by 10.6 oz (300g), close the valve, check for leaks again (there was a leak check at the beginning at about 14 psi), then start the engine, open the low side valve again and charge until the weight of the can has reduced a total of 21.2 oz (600g). I'm using storebought gauges and the small 12 oz cans of refrigerant. This service manual is the one that the dealers use so I'm assuming it's referring to the large tanks they use.

The issue is that the weight of the can has only reduced about 4 oz and is not going very fast at all. Does it just take a long time or should I start the engine now? There are no leaks.

TIA,
Daniel
 
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  #2  
Old 06-05-05, 10:12 AM
Member
Join Date: Feb 2005
Location: Michigan
Posts: 335
well i'v been doing a lot of ac work recently so im going to guess on your problem
There is a pressure switch on the high side that will keep the compressor from engauging if there is too much or not enough pressure. Therefore when trying to recharge it you are not getting any pressure in the high side because the compressor is not kicking on. So you can try to bypass the switch by connecting the right wires on it, or you can connect the compressor straight to your battery. Also it is recommended that you have the system vaccum pumped out before you fill it. when filling, if the can gets too cold, it will no longer charge, because the liquid inside cant boil and create enough pressure. so i usually end up taking it off and putting the can in a jar of hot water once or twice until it is empty. Good luck, let me know how it turns out.
 
  #3  
Old 06-05-05, 12:34 PM
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Join Date: Dec 2003
Location: Indiana
Posts: 312
Originally Posted by zzzz1486
There is a pressure switch on the high side that will keep the compressor from engauging if there is too much or not enough pressure. Therefore when trying to recharge it you are not getting any pressure in the high side because the compressor is not kicking on. So you can try to bypass the switch by connecting the right wires on it, or you can connect the compressor straight to your battery.
VERY, VERY, VERY BAD ADVICE!

Man, what happened to all the moderators around here?

zzzz1486:
The high side pressure switch will have absolutely nothing to do with preventing the system from charging. If everything is as it should be, a 95-100% charge should be possible without running the compressor at all. As a matter of fact, it's recommended to NOT run the system to charge with 134. The warm water trick can be of assistance, although I can honestly say I never had to use it through hundreds of 134 services.

DanTheMan:
You never stated why the clutch replacement was necessary? If you do not have the tooling/ability to put the system in a vacuum, take it to a pro and be done with it before you cause yourself more problems listening to uninformed and inexperienced advice like above. Never bypass the compressor controls or jeopardize the integrity of the electrical system. I assume you're new to this forum. There are several experienced techs who frequent this forum, and are extremely helpful. Most will also discourage A/C as a DIY operation due to the experience, training and tools required to perform the work properly and safely. Just remember, most worthy advice comes from those who state there qualifications in their signatures.
 
  #4  
Old 06-05-05, 01:01 PM
DanTheMan
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Well I continued on with the procedure since I hadn't gotten a forum response yet. I followed the instructions on the refrigerant can which said to start the engine. Once I had done that, the system started taking the refrigerant just fine at a steady rate, and the pressure on both high and low side looked more like what they should be according to different sources I had read. New clutch works great (The stator in the old clutch was failing, and as a result the compressor would cut out when heat levels were high (thick slow rush hour traffic, etc). I did use the hot water trick which helped speed up the process, but if I hadn't started the engine (I was using the small 12 oz cans of r134a, not the big tank that shops use), I would've been there all day. But hey, thanks! =>

Oh also, the official manufacturer's service manual that the dealerships use is what we have--it said after putting 10.6 oz of refrigerant in the system, close the valve, check for leaks, start the engine and run the A/C, and reopen the valve, adding another 10.6 oz for a total of 21.2 oz.
 
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