AC help (1 Viewer)

[landtank]

First day today that was hot enough for me to turn on the AC verses opening the window. Well al I got was a cool breeze. Remembering past threads on thge subject I bought a guage set and a can of 134a as I think it's only a recharge needed, more like hoping I think.

Any advice on hopw to approach doing this would be greatly appreciated. Should I take some readings first and what would they tell me.

Thanks

 

[Montana Cruiser]

Rick -

Take a look at this thread;

https://forum.ih8mud.com/showthread.php?t=18886&highlight=recharge

I was coming home from Boston today and flipped on the A/C for the first time to be met with cool air ...... but not cold, so I have been looking into the same thing this evening.

Nate

 

[landtank]

Thanks Nate, but what I was really hoping for was a new thread that would be more concise with the advice verses bouncing all over the place and might offer others assistance as alot of us are all just starting up our ACs now for a new season.

 

[cruiserdan]

Hook up the gauges per the FSM and check the pressures. Ther also is a trouble-shooting chart I believe. As long as the system is still holding some pressure adding refrigerant will likely be the ticket. If it's way down you may want to throw some dye in it as well to see if you have a leak worth chasing. Do you cycle the system once in a while during the winter?

 

[NSP]

I just went to Walmart bought the fix can with the hoses and two r134's....I am by no means a mechanic but this couldn't be easier on the LC, make sure you fill the L and not the H (so I am told). Start to finish probably took 15 minutes and could have been faster but I didn't know when the truck stopped taking the refrigerant.

Anyway, she is blowing ice cold....sweet....

 

[landtank]

AC is on all winter, it helps with defrosting

I've been reading up a little and the instructions with the gauges said that if the high side was low, add 1 can of freon and then recheck. Can I just leave the guage on the high side and fill until it's at the correct pressure? It would seem that the 1 can thing could over fill the system.

I do get some cooling, just not up to where I'd expect it. I'll start with the 10.00 can and then recheck the pressure over time to see if it looks like there is a leak. But I'm hoping that it's just an age/mileage thing and needs a recharge.

 

[Rich]

I just went to Walmart bought the fix can with the hoses and two r134's....I am by no means a mechanic but this couldn't be easier on the LC, make sure you fill the L and not the H (so I am told). Start to finish probably took 15 minutes and could have been faster but I didn't know when the truck stopped taking the refrigerant.

Anyway, she is blowing ice cold....sweet....

How did you determine how much refrigerent to install?

 

[cruiserdan]

How did you determine how much refrigerent to install?

S.W.A.G.

 

[landtank]

All done and not that bad either. I checked both the low side and the high side which they both seemed to be at about 60% when calculated with the air temp. So I monitored the high side as I added freon until it hit the proper pressure. It took about 3/4 of a can so I'm glad I didn't just dump in a can and call it good.


Only problem I had was after I mounted the can of freon and turned down the needle to puncture the can I couldn't get anything to come out. After about 10 minutes of futzing with it I realised I had to then back out the needle to release the freon. That's probably in the instructions somewhere .

 

[medtro]

What is the before and after high and low pressure, at idle and 1500 RPM?

What is ambient temperature?

 

[landtank]

low was 24 and high was 125. I then added freon til the high was 200 for 80deg ambient temp.


Been driving around and the AC seems fine.

 

[flintknapper]

You did it correctly.

low was 24 and high was 125. I then added freon til the high was 200 for 80deg ambient temp.


Been driving around and the AC seems fine.

Looks like you're spot on, and you did it correctly (using gauges).

Be sure to "purge" the lines on your gauges before adding freon also, so that you don't introduce any air into the system.

Someone asked, how do you know how much freon to put in?


ANSWER:

The Pressure Temperature Relationship varies with ambient temperature.

Here is a guide line for R-134a (R-12 is slightly different).

Low Side..........High Side..........Ambient Temp. (F.)

16-29..............115-200..............70-80 deg.

19-39..............140-235..............80-90 deg.

25-43..............165-270..............90-100 deg.

37-51..............210-310..............100-110 deg.

As you can see ..."figures" rise as the ambient temp. rises.

Every system is designed to work (most efficiently) at a certain rate of charge (freon) and with a certain amount of oil. It goes without saying...you don't want air or water in the sytem.

You CAN just dump some freon in your system (if its low).. and if you don't grossly overcharge it, you will likely get cooler air at the vents. For some people this is acceptable, and in an emergency its perfectly fine.

Be aware, that by under or overcharging..you are going to give up "vent temperatures" of perhaps 8-12 degs. The difference between 40 deg. and 52 deg. vent temps will be readily apparent. Gauges let you optimize the charge, as well as point out possible problems with your system.

All in all....if you can achieve vent temps that are 30-40 deg. less than ambient, you're doing pretty darn good.

 

[landtank]

Be sure to "purge" the lines on your gauges before adding freon also, so that you don't introduce any air into the system.

LOL, Yes I did.........by accident. While I was trying to figure out why the freon wasn't flowing I backed off that needle valve a couple of turns to confirm that was the problem. I did this while the hose was still attached so the freon flowed out the end of it.

 

[alia176]

Flint,

I have to convert one of my car from R12 to R134a. After I have a shop discharge the old Freon, I was going to change all O rings, drier, etc.. Question I have is what to do about the compressor oil change. Do I change it myself by removing the compressor or let the shop do it by evacuating it out with their machine?

 

[flintknapper]

Flint,

I have to convert one of my car from R12 to R134a. After I have a shop discharge the old Freon, I was going to change all O rings, drier, etc.. Question I have is what to do about the compressor oil change. Do I change it myself by removing the compressor or let the shop do it by evacuating it out with their machine?

I don't know what vehicle it is you're wanting to do this to, so I don't know if your old compressor is even 134a compatable. Most will do a decent job if they are in good shape.

You need to get ALL of the mineral oil out of the system. Basically this means flushing the individual parts (manifold hoses, condenser, evaporator), all of these need to be solvent flushed.

Replace O-rings with HNBR (they have a higher temp. rating) and get a bottle of "nylog" thread sealant (the best 6 bucks you'll ever spend).

The only good way to change the oil in your compressor is to flush it with (the same oil) you intend to use in the system. Put the comp. in a vice add 20-30cc. of oil in the suction port and turn the compressor by hand using a speed handle.
Continue adding oil until you get a clear stream of "new" oil. Then you'll need to drain it all out and add the proper amount back in. I like to put an ounce in the new drier, an ounce in the evaporator and the rest in the compressor.

Depending on what kind of condenser you have....it might not perform as well with 134a as it did with R-12. You will be using less 134a to recharge. The best solution for old "tube and fin or dual pass" condensers is to replace with a parallel flow. Even a large PF cond. is less than a $100.00

Don't flush any lines that have a "muffler".... just replace. Always use a new orifice tube.

Some systems require adjusting your cycling switch, and/or adding a Low/High pressure cut out switch.

Heres a good source for parts &info: http://www.ackits.com/

Good luck and cheers.

 

[alia176]

Thanks for the info. I have done most things you mentioned except the oil in the compressor. There's a oil hole in the side of the compressor that I'll use to drain the old oil and fill with new PAG oil. I'll hit you offline with more questions.

Thanks.

 

[cruiserdan]

I gotta jump in here 'cuz this is driving me NUTS.........

"FREON" is a trade name, coined by Dupount, for R12. R134 is NOT freon.

 

[flintknapper]

You right!

I gotta jump in here 'cuz this is driving me NUTS.........

"FREON" is a trade name, coined by Dupount, for R12. R134 is NOT freon.

That is true. Its like saying "lets go get a Coke" when you might really want a 7-up.

I'm guilty of it, I admit.

Wouldn't it be nice if there was just one product that you could add... like adding oil to your Cruiser. Just "pour in" the cold stuff!

 

[MoJ]

S.W.A.G.

SWAG?

S? Wild Ass Guess????

 

[cruiserdan]

Scientific