A/C Conundrum

[Dauber]

Hi guys I posted the following post on the air conditioning board I found from this forum but I was wondering if I need to have a clutch fan on my 83 6.2 for the a/c to work properly? thanks

here is the post:


Joined: 24 Jul 2005
Posts: 2
Location: Fresno

PostPosted: Sun Jul 24, 2005 9:05 pm Post subject: 83 Suburban A/C problems, please help Reply with quote Edit/Delete this post
I have a 83 C20 6.2 diesel suburban w/ rear a/c that I am building back up to a nice SUV. I purchased this last year and someone had already converted it to R-134a. I tried charging it myself and it leaked out within an hour so I brought it a shop I use for repairs. After finding two leaks and charging it up it would only cool down to 70 degrees at the vent. I bring it back and they tell me that the compressor is not bringing the low side down so they want to change the compressor. I said fine, I want to make everything work and plan on keeping this for a while.
New compressor, new accumulator, new orifice, new expansion valve on the rear unit later and 4 1/4 lbs of freon later it only cools down to 60 degees, now it has been about 105 degrees here for the last week, but it should still cool colder than that. When I check it at night it cools down to about 45 degees at the vent when the outside temp is alot cooler. The shop I had the work done at suggested that I put valves on the heater hose line so I could manually turn off the fluid from circulating to the heater core, so I did this cheap attempt and still no luck.
I have come to the conclusion that the shop I took this to had no idea how to fix this probem from this point, in fact the guy that was working on it told me "its trial and error at this point." He is a nice enough guy but before I bring this to a specialized shop and get charged a bunch more for no results I was wondering if anyone had and helpful suggestions. Thanks
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Chick


Joined: 28 Jun 2005
Posts: 380
Location: New Jersey

PostPosted: Sun Jul 24, 2005 9:25 pm Post subject: Reply with quote
First, if the fan clutch is more than three years old, change it. Then once good airflow is restored, you may be low..Pressures will tell. But you need a strang fan pulling the air across the condenser..If that doesn't help, post back..Hope this helps.
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Dauber


Joined: 24 Jul 2005
Posts: 2
Location: Fresno

PostPosted: Mon Jul 25, 2005 12:56 am Post subject: Reply with quote Edit/Delete this post Delete this post
chick thanks for replying,
I do not have a fan clutch, its direct drive. I think it is suppose to have a fan clutch but It probably was replaced with this one when the engine rebuild was done about 30k ago-because the 7 blade fan looks new as well as the housing that attaches to the pully.
I just replaced the radiator last month so that is new, maybe I should mount and electric fan of some sort in front of the condensor?

[DmaxMaverick]

I feel your pain! Temps around here have been just a couple ticks lower than yours. The Valley hasn't been nice to us lately. Your conversion on that older system sounds like typical results. The condensor is just too small for 134a and this heat. The direct fan coupler would more likely help your condition, not hurt it.

I've done a couple R12 to 134 conversions. The later models (93+) aren't so bad, but earlier than that, and it will only put out at higher RPM's with good airflow. They are fine at highway speeds, but fall flat in the city, or idling. We've tried electric fans, and they help very little. Your direct coupler would be even better than that. My Blazer was converted to 134, then back to R12. With R12, you could use it as a meat locker. R134 was OK when I was doing the long commute, but was worthless below 40 MPH. I even installed a lower thermostat to keep the fan clutch engaged, but it was still not working. If outside temps were below about 85, it worked OK. 105+ was out of the park.

In your situation, a 30

[Dauber]

Thanks for the post DMAX-
Buy saying upgraded equipment I guess you mean going back to R12 or the larger condenser. That 60 degrees is at highway driving, city it goes up from there.

[Peter J. Bierman]

I have been fidling with my selfbuild A/C ( build from various available parts )and found that with a little less charge the A/C performes better.
The low side pressure will not be affected realy but on the high pressure side there is a lot less pressure and therefore less heat to cool by the condensor.
For a converted system a lower charge might be a sollution.
In my case, the differance was 7 degrees celcius @ 1000 rpm and stationairy in the workshop!
The charge is now 200 grams lower then before.

Hope this will help.

Peter