New ac not working correctly
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New ac not working correctly
Hey guys I just put a new ac system in my truck and doesn’t seem to be too cold it fluctuates between maybe 65-75F. I put in a new compressor, dryer, condenser and evaporator, orfice tube. I pulled a vacuum on system and let sit over night, held vacuum no leaks. I put 8 oz of oil in system and 3 1/2 cans of refrigerant around 42oz seemed to work good at first then got warm when I was driving then cold again, I put gauges on truck low side was 30 high side was 200. Same thing again today very hot here in Florida didn’t seem to blow more than 70 degrees during the heat of day. The compressor today seemed to be kicking on and off in quicker cycles, any sensors that can go bad or something I’m missing ??? Thanks
Fleet Mechanic
Joined: May 2010
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From: West by God Virginyuh
I think the correct amount for the pickup AC charge is 45oz, or 2.82lb.
Other than that it could be your pressure sensors in the AC system. But I’d say first thing to do is get charge amount correct.
Other than that it could be your pressure sensors in the AC system. But I’d say first thing to do is get charge amount correct.
Lead Driver
Joined: Dec 2006
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From: So. Jersey
With the gauges on it, run the A/C with the engine at high idle or have someone hold it at 1500rpm.
Watch the low side pressure. If it is dropping down to 20ish and kicking off, then kicking back on once the low side pressure comes back up then you are under charged. You probably need to add more. It should just about stay on fully at high idle. I usually add a little at a time to make sure the short cycling improves. The longer the duration it stats kicked on the better of course. At the same time watch the high side. If you add too much then you will have the High side switch kick the compressor off which you'll observe on the gauge.
Watch the low side pressure. If it is dropping down to 20ish and kicking off, then kicking back on once the low side pressure comes back up then you are under charged. You probably need to add more. It should just about stay on fully at high idle. I usually add a little at a time to make sure the short cycling improves. The longer the duration it stats kicked on the better of course. At the same time watch the high side. If you add too much then you will have the High side switch kick the compressor off which you'll observe on the gauge.
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So I just put gauges on again and reved up to 1500, low side is about 40 and high side is jumping up to 300, does this mean something is clogged??? When I got a the new evaporater the arm going into dryer was bent so I carefully bent back I’m wondering if I possibly kinked just enough, or orfice tube wrong way???
Lead Driver
Joined: Dec 2006
Posts: 6,496
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From: So. Jersey
Did you replace the orifice? I have had a similar result you're having after I replaced an orifice and what happened was i drew vacuum and fed the refrigerant in so fast it dislodged and blew apart the orifice tube. I found it apart when I removed the line to inspect it.
You definitely want to replace the orifice and dryer fir that matter when the system us opened up.
On edit: I had to go back and read and see you did replace it. It's a tough call since I wasn't there when you filled it but the orifice valve coming apart certainly is a possibility if you filled it backwards like I did one time.
You definitely want to replace the orifice and dryer fir that matter when the system us opened up.
On edit: I had to go back and read and see you did replace it. It's a tough call since I wasn't there when you filled it but the orifice valve coming apart certainly is a possibility if you filled it backwards like I did one time.
Senior User
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What do you mean you pulled a vacuum? How much vacuum? Evacuation isnt as simple as a leak check my friend.
Also, how do you know how much refrigerant you added? You should be charging with a scale unless you know what to look for on pressures. Charging a system like this with gauges is hard mode for sure. These have very specific capacity systems.
Also, how do you know how much refrigerant you added? You should be charging with a scale unless you know what to look for on pressures. Charging a system like this with gauges is hard mode for sure. These have very specific capacity systems.
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Fleet Mechanic
Joined: May 2010
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From: West by God Virginyuh
The 300 high side and 40 low side is close to what my truck was putting out, but mine was at idle. I think my low side was more around 50, or even 60. But that was a year ago when my friend and I did the AC at the Ford dealership so my memory is not 100%.
The 200 high and 30 low you had earlier is way too low. That you’re at 1500rpm and now barely at what I was getting at idle would make me think you are low on refrigerant. But I’ve been known to be wrong in the past.
The 200 high and 30 low you had earlier is way too low. That you’re at 1500rpm and now barely at what I was getting at idle would make me think you are low on refrigerant. But I’ve been known to be wrong in the past.
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