A/C window unit cool but not cold
Posted 11 June 2006 - 06:04 PM
Posted 11 June 2006 - 08:39 PM
Posted 12 June 2006 - 02:42 PM
I had a formal training class on sealed systems, but it has been a few years ago. Been doing appliance repair a few years, but not any sealed system work. We have the equipment here at the shop that the previous tech, who did sealed system work, used. What is the best way to determine if and where a leak is? Bubble solution? If freon is added, can it be added without purging the system first? Just looking for some direction.
Posted 12 June 2006 - 08:25 PM
Sounds like a window unit. Soap bubbles can be used, but an electronic or halide torch leak detector would be better. Just look really carefully with the bubbles.
If U have a gage set, unless someones already added some, your gonna have to go to a HVAC supply house and get a (2) inexpensive multi-pipe size Tap-a-Line valves. Very easy to use. Be sure to use the correct insert for your size pipe. The valve should not be loose on the pipe nor should it be crushing the pipe. Follow the directions. Word of caution-there is probably gonna be a very small black rubber o-ring included with ur valve. Very easy to loose. Don't loose it!!
Most compressors have a process tube on them. Look 4 piece of copper pipe coming off comp going to nothing and crimped on the end. Install 1 valve on that pipe(between the comp and the crimp). Thats ur suction (low, the blue gage:)) side connection.
Next look @ the compressor. The 2 pipes connecting 2 it. 1 line is bigger then the other. U want the smaller 1. Install a valve on it. Thats the discharge (high side, the red gage;))
Make sure your hoses are connected tight on the manifold. Hook up the gages. With unit off both gages should read at least 125psi @ 70 degrees ambient temp. Unless its really cold they shouldn't B much lower then that. If they are lower, U have a leak.
Hope that helps:)
Posted 13 June 2006 - 04:57 AM
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Posted 13 June 2006 - 05:12 AM
Posted 13 June 2006 - 12:54 PM
Posted 14 June 2006 - 08:01 AM
Low side went down to about 6 psi, while the high side went up to about 130 psi. After it ran for about 5 minutes, the high side was up to about 165 psi and the low side had risen to about 33 psi. After 5 more minutes the pressures were about 170 psi and 35 psi.
Posted 15 June 2006 - 03:58 AM
Posted 15 June 2006 - 10:42 AM
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Posted 18 June 2006 - 10:05 AM
Ok. It sounds like U R short of gas. Couple more checks should do it. Is the unit using R-22? If it is and U have a Temperature/pressure (T/P) chart, start the unit again and let the pressures settle out. Measure the ambient air temp (room temp), add 30 degrees to it. Find that temp on the T/P chart and then read the corresponding pressure 4 R-22.
Example-- room temp =70 degrees. Add 30. New temp is 100. At 100 degrees your head pressure (high side) should B approx 200psi (+-15 psi ). We can also say that at 200 psi head pressure ur suction (low side) should B approx 60 psi(+-5psi) Now U know what ur pressure should be(approx). If its 80 degrees, then head pressure would B 230 psi 4 R-22. U have to adjust accordingly.
So ur running @ 165 hi and 35 lo. Hook up to a tank of R-22, purge the air out of ur gage hose and add some gas to the unit slowly thru the lo side. Watch ur hi side gage to C if the pressure starts to rise as U add the gas. If it does thats good. Bring UR hi side pressure up to 200 psi and stop. Has the low side gage pressure also gone up? If yes, then most likely U have lost some refrig to a leak. Although with window units it can B tricky.
They hold such a small charge that if many ppl have hooked up to it with gages, over the years they have actually taken enough refrig out to make it look like U have a leak. A six foot refrigerant hose can hold approx 2 oz of refrig. After 4 hook ups, if no one adds refrig, U are now down 1/2 lb of refrig. If the unit only holds 34oz full charge, UR now down 1/4 of the full charge;) with no leak.
If both of UR pressure rise when U add gas then continue to add gas until U reach the desired head pressure you figured out earlier. Once U reach good pressures take a thermometer and measure the return air temp to the unit and the cold(supply) air out. UR looking 4 a 20 degree spread(+-4 degrees, 18-22)
If U have that U can now either start looking 4 a leak or let the unit run 4 a day or to and C if your pressures start to drop again. Set it at a normal temp and let it cycle on and off.
If U add gas and the pressures don't start to rise then U may be dealing with a restriction.
Hope that helps.
Posted 23 June 2006 - 04:05 AM
Again, thanks for the help, I've learned a lot.
Posted 24 June 2006 - 09:58 AM
U are welcome:) That 230/70 sounds great. Don't let the fluctuation in head pressure throw U. If the OAT(outside ambient temperature) has gone down , so will UR head pressure. Vice a Versa if the OAT has gone up. U must always check Ur running head pressure against UR T/P chart and the OAT at the time.
If both of UR pressures continue to fall, then yep, U have a leak.
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