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Only blows cold while IDLE.

metalgod3082 on Fri May 07, 2010 5:01 PM User is offline

Year: 1999
Make: Nissan
Model: Maxima
Engine Size: 3.0L
Refrigerant Type: R-134a
Ambient Temp: 90
Pressure Low: 45-50
Pressure High: 175
Country of Origin: United States

I'm opening a new thread as I did not measure the pressures correctly on my last thread and I don't want everyone to have to read through the 18 posts to know what's going on.

My car seems to only blow somewhat cool air when it's idle. Once I start driving it will then start to blow ambient temperature air. I brought my car to the shop and they told me the expansion valve was stuck open. I replaced the expansion valve, evacuated the system and recharged but am still having the same issue.

Here are the readings when my car is sitting in park at 1000 RPM:

Ambient temp = 90
Low Pressure = 45-50 (the needle fluctuates back and forth between these 2 numbers)
High Pressure = 175
Inside Temp = 60

Here are the readings at 2500 RPM after about 5 minutes:

Ambient temp = 90
Low Pressure = 95
High Pressure = 140
Inside temp = 98

So the low side rises and the high side drops when engine is revved.

Now what I tried was while the engine was revved to 2500 RPM with the inside temp of 98 I had a friend mist the condenser and after a few minutes of misting it the temperature dropped to 60 again and the low side pressure dropped back to 45-50.

Can anyone give me some insight as to what the source of the problem would be? TIA

mk378 on Fri May 07, 2010 8:11 PM User is offline

Put the interior fan on low (or unplug it entirely) and try the test again. If you get lower low sides that proves the TXV is working. Looks like your compressor is a quitter. It's not a SD7V16 by any chance?

Edited: Fri May 07, 2010 at 8:12 PM by mk378

metalgod3082 on Fri May 07, 2010 8:32 PM User is offline

Hopefully the TXV is working as that's what I just replaced that did not fix the issue. This is the compressor that I would need for my car|GRP60000_613365928___

After coupon code it would be $211 free shipping. Does that sound like a good deal? Are you pretty certain its the compressor that's failing with those readings and tests I did? I'm in AZ and getting kinda desperate for A/C and would like to order the parts soon so I can replace them next week sometime. Thanks again for the help!

metalgod3082 on Mon May 10, 2010 2:59 PM User is offline

Any other insight to this? Does everyone agree its the compressor? It's getting hot in AZ and would like to order the part soon. TIA

Prospeeder on Mon May 17, 2010 9:30 PM User is offlineView users profile

Im gonna say bad cooling fans, damaged, clogged or dirty condensor isnt removing the heat from the refrigerant and causing a big rise in pressure and lack of cooling

1990 Pontiac Turbo Grand Prix
1990 Pontiac 6000 LE V6
Both have R12 A/C

NickD on Mon May 17, 2010 10:55 PM User is offline

In a properly charged system the low differential pressure is a sign of a weak compressor, more than likely weak leaf valves. What happens at 2,500 rpm, 2,000 is plenty when you switch off the compressor, do your gauges equalized quickly? Should take around 30-45 seconds.

dockyN on Tue May 18, 2010 1:00 AM User is offline

not very sure,it may compressor's pro

metalgod3082 on Fri May 21, 2010 7:14 PM User is offline

Just wanted to say thanks for all the help, got it all fixed. Turns out it was the compressor.

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