Model: Civic Si HB
Engine Size: 1.6
Refrigerant Type: R-134s
Ambient Temp: 80
Pressure Low: 40
Pressure High: 350+
Country of Origin: United States
Here is my problem, My AC only works when I'm driving
Before this problem I installed a whole ac system(compressor, condenser, drier, low and high side lines, and evaporator) since my car was jacked up from the beginning with all the ac components. I got the donor system from a junkyard. The car system still had freon so i knew the system was still in good shape. Not to mention this is my first time doing ac work. So when I installed and recharged the system the ac blew at 45 degrees F at the vent on Idle (1000rpm) ambient air temp 80F, humidity 50%, windows rolled up, and blower fan at max. Thing was that the connector on the drier wasn't sitting properly so I had fix that. The system worked liked this for about 5 days then I went ahead to fix the drier line.
When I got the system evacuated from freon. I disconnected the drier line and a whole bunch of oil came out (I guess the system still had some freon)! So I poured some oil into the drier and continued to put the lines back together. After fixing the drier line and putting an extra o-ring at the line because it couldn't hold a vacuum . I vacuumed the system and held it at -29hg for 30 mins then turned it off to check for leaks for about half an hour. Leak checks good so I continued on with charging the system. This is my third time charging this system with about 18oz of R-134a. I used two cans 12oz each but purged the gauge lines of air.
So now when I checked to see if the air got cold it held at 55F at the vent on Idle (1000rpm) ambient air temp 85F, windows rolled up, and blower fan at max. It held good and pressure readings were at low side 40 psi high side 210psi.
Next day the car only started to only get cool when driving. It got cool after about 2 mins of cruising at 50-60mph, 3000rpm, and vent temp would be around 55-60F at 85 Ambient air temp. Then when at idle at a stop light the temp would go up like the ac ain't working at all. This is becuase my compressor would cycle off every 1-2 minutes at idle then turn on after 3 mins then it would repeat that whole process just at idle. I can't tell if the compressor cycles off/on when cruising at all.
Gauge readings after all this happened: Hooked up gauges engine not running saw static pressures low and high side equal at 75psi. Started car then low side reached 45psi and high side would climb to 370psi then shutoff ambient air temp 80F. This process would repeat itself at idle. The condensor fan would stay on whenever I turn on the ac and only shuts off when the ac is off.
At night, ambient air temp 70, and driving the vent temp would be 43F. It would still heat up though when sitting at Idle.
I'm thinking my TXV is fine becuase the temp still reaches 45 degrees at vent when driving, blockage somewhere, or I have too much of something in the system. I'm thinking about flushing the whole system, replace the txv and drier, then recharge. But i'm running out of funds.
Well what do you guys think is the problem?
94' Civic Si HB
Edited: Thu June 16, 2011 at 1:03 PM by bigJOE671
sorry wrong thread.
Edited: Thu June 16, 2011 at 12:49 PM by HVACNY
R134a and not an adequate condenser for heat removal.
Go back to R12 or update the condenser.
Two whole cans is going to be too much refrigerant. You don't lose that much when purging the lines. Also be careful of too much oil. Used parts could have a lot of oil in them. Finally, that model lets a lot of road debris hit the condenser (especially the bottom half) and mess up the fins, which will impede heat transfer. It's cycling on high pressure, so you know the compressor is OK.
The times that I'm really glad that I have AC is when I'm sitting in a traffic jam and it's cooking outside, lol. It'd be nice to get yours fixed so it's working properly.
I would buy a brand new drier instead of using the one you got from the scrapyard. Just because the system you took it from still had pressure, doesn't mean that the drier is in good condition. Also, out of curiosity, when you say drier, do you mean a liquid line drier on the high side, or a suction accumulator/drier?
A low-side pressure of 45psig should have a saturation temperature within the evaporator of around 50F. It seems like the temperature while you're driving is around that. The fact that your evaporator temp/vent temp is so high when you're at idle suggests that there is no liquid through the TXV and no boiling within the evaporator. That, and the fact that your discharge pressure gets so high could be attributed to a blockage in the condenser or at the TXV, poor airflow over the condenser, or a high amount of superheat from the suction gas or during compression.
Since your low side pressure remains at 45psig, I would assume that refrigerant is still getting back to the compressor (but that depends on where you're reading your low-side pressure from). I'm also not sure if your compressor it cutting out on high pressure before the low side has a chance to drop significantly.
I would evacuate, change out that drier. Blow out the condenser to see if it's become oil logged. Inspect the TXV for foreign material, or replace it.
A way to test your condenser to see if it's sufficient for your system, is to take note of your high side pressure, and look up the corresponding saturated temperature on a PT chart for R134A. Take the temperature of the condenser outlet line, and compare it to that saturated temperature. The outlet temp should be colder than the saturated temperature, and the amount of cooling past the saturation temperature is called your subcooling. I would hope to see between 10-30F subcooling in the condenser.
There is no knowledge that is not power
Give an update on how it goes. Also double check your install of the drier/receiver. Some are bi-directional and some are one-way. I don't know the connection style makes it possible to have it hooked up backwards, but it's worth taking a quick look.
There is no knowledge that is not power
I apologize for the late update...got really bizzy cuz of the NAVY
I found out the problem!
It was the condensor fan motor!
it was spinning when i first checked it but it was going out. So I was thinking it was everything else that could cause the problem. Therefore, not providing sufficient cooling to the hot side. Now the motor doesn't even work. I was spraying water at the condensor and the ac was blowing around 68 degrees at the Vent with ambient air temp at 89 degrees.
94' Civic Si HB
Edited: Wed July 27, 2011 at 5:28 PM by bigJOE671
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