Hey all,

I noticed lately that either my ac is not as cold as it used to be, or I just hadn't ever used it when it was really hot (I normally use windows when my wife isn't with). Its still cool, just not ice cold. I have also noticed in the past that at idle my ac compressor will lock and unlock regularly. I was reading about ac issues now to try and see whats up and discovered that the locking and unlocking probably means my system is low on pressure. Now I'm looking for advice on how to deal with this. Should I try a do-it-yourself can from autozone? Ive been told in the past they are dangerous and not the correct way to service the system, but I've been reading and a lot of guys say they use them with great success. Is it worth a try or not?

I am by far no ac expert but here is my  worth. The diy cans will work, you just dot have a way to check the high and low side pressures. Some of the cans come with a pressure gauge that you can observe the low pressure side. You need manifold gauges to read both sides. I dont see anything wrong with shooting some in there and get your compressor stopped from short cycling. If you have a copy of the FSM there is alot of good info about the AC system. In short they will work you just dont know what is going on in there. Plus you do not have to use the whole can. Maybe some one a little more knowledgeable will add to this. And be careful the high side pressure of these things can hit 300 psi or so.

 

 I just got mine up and running after about 4 years of it not working, long story that i want get into. I replaced my high side line and the accumulator, pulled vacuum on the system and it would not hold. Finally had to shoot some freon in there and found the leak. Got it fixed and now have cold air, not ice cold but cold. I bought a set of HF manifold gauges and vacuum pump, $50 and $150 respectively and they seem to work fine. It seems I may still have a problem since I have low low side pressure and high high side pressure. Yesterday I had good low side and slightly high high side pressure, but today a accidentally vented freon from the high pressure side and that is when the readings changed. So I am going to add a little more later and see what happens. Not trying to hijack this is all for another thread.

Edited August 2, 20168 yr by dripley

You probably have a small leak at the evaporator (heat exchanger inside) and/or the O-rings at the connections are 'dried out'. The best way would be to leak test the system, reclaim, repair, evacuate and recharge with the proper amount cost about $80-$? depending on what's leaking or for about $20+ you can top it off yourself.   It's not hard to recharge/top up the A/C system, but best to use a pressure gauge so you can see if there is a problem with the expansion valve or compressor and all so not to over charge the system.

  If it's cool now you probably need 1 12oz can to top it off but with pressure gauges you can use the chart below to get close to max fill.  Walmart sells recharge cans with low pressure gauge.

http://www.walmart.com/c/kp/r134a-recharge-kits  

 

 

Thank you gents for your advice! I do have a copy of the FSM and will check it out. It is actually open on my computer as I type this from looking at other things lol. For some reason I still forget to check that thing. Not used to having such a useful resource like that yet I guess. If it is a leak under the dash, that will have to wait for some time in the future when I rebuild my dash :-) Are there any other connections with o rings that can re replaced?

I believe I've seen some refrigerant plus leak stopper, I wonder if I would benefit from that?

According to the fsm the clutch cycling repeatedly could also be a faulty low pressure switch :-/

Edited August 2, 20168 yr by leathermaneod

You can get to all of the o ring connections from under the hood. Even the evaporator connections are there next to the fire wall. Just follow the lines and you should be able to see them all. Some are easier than others to work with. The compressor has gasket on it too and they were surprisingly easier to do than I expected. The leak I had ended up being the at the high pressure line coming out of the condenser. To me that is the easiest one to get to. I should not have leaked beings it is also the easiest on the check and be sure the joint is completely seated. So a  on me..

Hmmm glad to hear they are all accessible! I am wondering how I should handle this now. Replace all seals, then get the system recharged, or try a can myself first and see how long it lasts. What would you guys recommend? Do you have a source for all the seals? Part numbers? Approximate price?

 

 

I'd dump a can in and see how long it holds.  If over a year then stay with that, if less than a year then repair the leak.  O-ring kit at O'Reilly's.  You'll also need a spring lock coupling tool to get the lines apart.

      http://www.oreillyauto.com/site/c/search/A!s!C+System+O-Ring+&+Gasket+Kit/06500/C0320.oap?year=2000&make=Dodge&model=Ram%2B2500&vi=1361999&keyword=a!s!c+o-rings

Edited August 2, 20168 yr by IBMobile

This is what I bought for $15 at Rock autohttp://www.rockauto.com/en/moreinfo.php?pk=3923958&cc=1440064&jsn=10482&jsn=10482 At the time I did not realize that the whole system is orings except for the compressor. They are more like large sealing washer for fuel connections. They were included but all the big odd shaped are not on my truck. A good assortment of o rings would have worked as well I believe, except for the compressor, not sure where to get them. All my new stuff came with o rings and spares plus I had an assortment box so now I could almost start an o ring store. 

 

If it were me I would just top it off and see if that helps. If holds for more than a year good for you. If it does not then repairs are in order.

                                           Dripley enjoying his A/C on the way to work

                                      

20 minutes ago, IBMobile said:

                                           Dripley enjoying his A/C on the way to work

                                      

This fits more than you know. I did get mine working again but while doing it I have knocked something loose on the vacuum side of things and only have cold air in the defrost. Gonna trouble shoot that one tomorrow. Another good picture by the way.

43 minutes ago, IBMobile said:

I'd dump a can in and see how long it holds.  If over a year then stay with that, if less than a year then repair the leak.  O-ring kit at O'Reilly's.  You'll also need a spring lock coupling tool to get the lines apart.

      http://www.oreillyauto.com/site/c/search/A!s!C+System+O-Ring+&+Gasket+Kit/06500/C0320.oap?year=2000&make=Dodge&model=Ram%2B2500&vi=1361999&keyword=a!s!c+o-rings

Rock auto has that one too. Only thing is you have 4 spring lock connectors. Even the big kit I bought only had 2. Mine were all still good and I reused them. The inlet to the condenser had one on it that was round on one side but the other side was square. I did not see one like that in the kit I bought so I used closest thing I could find in the kit and it is holding. 

@IBMobile Just a fair warning... I ran across a few weird vehicles with different standards of pressure or functions. Like I found a Honda that operates at as lo side of 15 but cycles automatically by computer control not pressure. I've seen some Ford vans as high as 55-60 PSI getting the full 4 pounds of freon in the system. I will admit for most vehicle A/C work I do follow the chart you provided but still highly suggest using a good manifold setup with both hi and lo pressure gauges is the safest way to go.

I was wondering if the chart @IBMobile posted was generic for all. And @Mopar1973Man seeing 4 pounds of freon in Ford van makes me wonder. My truck says 1.875 pounds and not sure what the wifes Saturn takes. I dont mind experimenting as long as the system does not explode in my face

1 hour ago, Mopar1973Man said:

I ran across a few weird vehicles with different standards of pressure or functions.

Thanks, The chart is generic but will work for a dodge truck.  I recharged a 2006 Volvo S60 last Friday with out side temp of 102° low side of 15psi and high side of 150psi, put in 16 oz  into a 1.6 lb system.  The low side never went above 35psi and the high side went to 300psi.  The duct temp was 20°. So by that chart the low side should have been 50-55psi.

2 hours ago, Mopar1973Man said:

Ford vans as high as 55-60 PSI getting the full 4 pounds of freon in the system

Is that with or without rear evaporator? 

There are a few weird animals out there. About the Ford it's with rear evaporator. 

Hey all,

well I tried adding some AC Pro today. It's 90° here so pressure was allowed to be 60psi max per fsm. When I first started the gauge would build up to about 45° in the ten seconds the compressor would run before shutting off. The air out the vents was a little over 60° at this point. I added a little freon (two times about 5 seconds each) and it would shoot up to a little past 55 psi on the gauge, then comp would shut off and go back down and only build to 45psi again. The air did get a little cooler, about 50° now, but I'm afraid I'll be over charging this thing if I add and more freon....my next move is to try the AC low pressure switch because the fsm says it can be the other cause for the compressor to cycle rapidly. Any thoughts guys? Anyone know how hard it is to replace that switch?

Edited August 4, 20168 yr by leathermaneod

 

1 hour ago, leathermaneod said:

I added a little freon (two times about 5 seconds each)

That not long enough to do anything. 

1 hour ago, leathermaneod said:

it would shoot up to a little past 55 psi on the gauge

When you first hook up a new can of 134A to a system that's running you'll get a high reading when the can is first opened due to higher pressure in the can than the low side.                                       

1 hour ago, leathermaneod said:

AC low pressure switch because the fsm says it can be the other cause for the compressor to cycle rapidly. 

Will the AC PRO set up let you see what the low side pressure is with out opening the can?  If so,

you can jumper the connector for the pressure switch with a paper clip this will keep the compressor on all the time. Don't let that jumper touch ground and don't run the AC system for a long time with out adding the 134A.  Now you will be able to get a low side reading and add as need.

Yes the AC Pro gauge will read as long as the compressor is cycled on and the can valve is not open. I'll try jumping that connector and see what the compressor charges up to. How long is too long to run the compressor with the low side switch jumped?

Well I followed your advice @IBMobile and so far I am very pleased with the results, though slightly confused. Heres what happened. First off, found the ground at the PCM to be doing nothing, it was very loose. So I cleaned and tightened that. Anyway, on the ac stuff. Unplugged the low pressure switch and jumped it, compressor stayed locked. Checked the pressure and it was only at 10 psi! Not sure how that works since before with the comp cycling it would go up to 45 psi....anyway added AC PRO in 10-20 sec increments checking each time. It took almost all of my 20 oz can and wouldn't go above 25 psi so that seems odd to me, not sure if that indicates I have a leak? I think it should have made it to at least 40 psi...anyway I stopped when it didn't go above 25 psi after a couple more tries and checked the air coming out the vents. It was VERY cold lol. My Harbor Freight temp gun, which I've always thought was fairly accurate, registered down to -30* when aimed in the vents! Really strange since before we charged the ac it was reading about 60* in the vents. Obviously it wasn't that cold, but I know it was very cold lol Thanks for all the help guys!

That's why I love my manifold set. I can read both the hi and lo side pressure making the best choices in pressure based on temperature. I typically place a thermometer in the vent and monitor better the manifold and the thermometer. Now @leathermaneod secret to said. The lower the lo side pressure colder it will become but... You need to have enough low side pressure to prevent cycling of the compressor. I can tell you that Dodge's lo side switch is about 25 PSI for cut out pressure. So typically I aim for about 30-35 PSI on the lo side. This will prevent excessive cycling while driving which you can see if you have a second person raise the RPM's to 1,500 RPM or so. The pressure will drop again on the lo side. 

Edited August 5, 20168 yr by Mopar1973Man

I'm a little confused Mike, are you saying I should set high idle or have someone hold it at 1500 and then attemp to charge it again? My compressor was staying locked at this point, but I couldn't get the pressure above 25 psi....

No. Just bring the RPM's up and see what your pressure are like. See if the compressor is going to excessive cycle out. Remember you DRIVE your truck not IDLE in parking lots. So the A/C should be charged enough to prevent excessive cycling. Now under normal operation eventually it will cool the cab to the point you turning down the fan speed. Now I except the compressor to cycle because the evaporator temperature will fall even more. So the lo side pressures typically fall more. Then mild cycling of the compressor will occur because of excessive cold temperaure and prevent freezing of the evaporator.

 

To see this happen roll up the windows let the cab cool on MAX A/C and now turn the fan speed to low and watch the lo side pressure it will fall to about 25 PSI and kick out the compressor. Look at the inner ring you'll see the discharge temperature is just below freezing. Optimally you want enough freon to keep the evaporator sweating. Hence why I normally head towards 35-40 PSI so when the vehicle is driven the lo side as close as possible to the freeze point without trip the lo side cutout.