Model: Blazer - Full Size
Engine Size: 5.7l
Refrigerant Type: R134a
Ambient Temp: 80
Pressure Low: + 25
Pressure High: 0
Country of Origin: United States
Replaced everything but the double hose from the compressor to the condenser and drier. (New condenser is parallel flow)
Installed 8 oz ester oil in the compressor, rotated the compressor a few times manually.
Installed 2 oz of dye in the hose to the compressor.
Turned the screw on the pressure switch 1/4 turn to the left to lower the switch pressure to about 21.
Evacuated the system for an hour, closed the blue valves, and let it sit for 2 days. When I open the Low side (blue) I get reading of about negative 27.
Attached R134a can, opened blue valve on manifold, opened the blue valve on the connector to the low side on the drier. Did NOT open the high (red) side .
Attached can to yellow hose, pierced the can (well i screwed the valve down as far as it would go), opened the valve.
Rotated the can back and forth for 20 min. Can does not get cold or feel lighter but the blue gauge went to Positive 25 pounds.
Jumped the pressure switch using a paper clip to activate the compressor.
Refrigerant is not going in.
Help, what am I doing wrong.
Just wanted to add. Engine warmed up and a/c on Max with fan on maximum.
Maybe your adapters and couplers are not working properly. Disconnect the can and try to evacuate again. Only this time, just open the high side valve to the vacuum pump. If you are indeed evacuating the truck, the low side will go down negative.
2 oz dye is way too much.
There should be no need to jump the switch. Start with the engine off and turn the can upside down to put in liquid. Repeat with another can or two until it won't take any more. Then start the engine and engage A/C and finish the charge as gas.
I think it was 2 oz. not really sure. There were lines on the side of the bottle of dye. I just put in till I got to the second line. There are 5 applications in the bottle and I am quite sure I put in only one application.
Will try evac on the high side in the morning.
Thanks for the fast response.
The Low (blue) side valves on the gauge and at the low side port were the only ones I opened.
I left them on for the 2 days because the truck is not ready to roll yet. I have rebuilt the entire truck body except for the hood, cab pillars and roof and still finishing up the interior.
Like I said, start the vacuum pump, open only the high side first. Observe that the low side gauge goes from zero into vacuum. If it does not, one or both port connections are stuck closed. If that checks OK, then open both sides to evacuate fully. After evacuating, do a leak up test, then pump again for a few minutes and proceed immediately to charge. Do not leave the system under vacuum without the pump running, as air can get in.
Edited: Tue September 10, 2013 at 10:10 AM by mk378
Started connecting them and I decided to look at the R12 to R134a hose adapters to see how the valves worked. Looking into the low side adapter I saw loose rubber. I pulled it out and found it was a rubber gasket and it was split and jammed into the center of the valve.
Since the high side adapter did not have one of these in it gaskets I pulled it out. When I put the connector on the low side it felt loose. Luckily, rare for me, I had another set of adapters. These do not have valves on the end of the hose but I figure it has to be better. After seating they feel snug.
Started suction on the high side and just like you said the low side vacuum went down. Switched over to low side just for the heck of it and the pressure gauge remains bottomed. Read's Negative one bar. Well below the -40 on the outside scale of the gauge.
Since I am not sure if I ever really had true vacuum I am going to leave it running, with both valves open, for an hour to make sure that any moisture is boiled out. I am concerned that the desiccant collected moisture when I left the damaged, likely leaking low side connected for 2 days.
Looked up leak up test on the net. I do not have recovery equipment. Is this essential ?
and, to test the vacuum what I have done is to close the valves on the manifold, connect the yellow hose in a loop to the manifold, then open the blue valve to test the vacuum level. Is that the correct way?
Edited: Tue September 10, 2013 at 12:17 PM by themcguire
Once your done your vacuuming with your pump still running close both valve on your manifold, leave them closed and see if the vacuum holds. Depending on your pump, you should loosen the hose or the other capped port to relief the vacuum and let in run for a few seconds before shutting it off that helps on the next start up plus being easier on the pump.
Edited: Tue September 10, 2013 at 2:05 PM by wptski
Ok will do that next time.
Let it run for about an hour. Then let it sit for 1/2 hour. No change in pressure. Started putting in r134a. Engine off. Very slow but the 1st can went in.
Then I had to leave for a Dr. appt. Just got back. When I left blue side was 29 positive. Just got home, No change in pressure on low side.
Will put in 2 more cans tomorrow.
Wonder if you know about parallel flow condensers. I contacted Spectra about the one I bought and they said the PF model I bought has the same volume as my tube and fin.
Read a post here a short time ago that says that if you convert from tube and fin to parallel flow you should put less R134a in. I was going to put 80% (42oz) in my 1988 K5. (Label says 52 oz of R12)
Charging on the low side with vehicle running, A/C on max, window open can be speeded up by putting the can of warm water no higher 125F and a large fan in front of the vehicle.
Finally got around to finishing this....
a/c now working getting less than 50 degrees with a/c on max, truck parked.
Not drivable yet.
Blue gauge reads 30 psi. Red gauge reads about 175 psi.
So I guess it was that bad low pressure adapter that was bad.
Thanks for the help.
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