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1991 Chevy van with dual AC - where to start?

Fishermark on Sun May 03, 2009 4:32 PM User is offlineView users profile

Year: 1991
Make: Chevrolet
Model: G20
Engine Size: 5.7
Refrigerant Type: 134a
Country of Origin: United States

Sorry for the long post with probably too many questions, but I just obtained a 1991 Chevy G20 Sportvan. The AC hasn't worked in years - I will be getting it running again. It was converted to R134a several years ago, but the van hasn't been used in years and has had no freon in the system for at least five years. My question is what to replace? I know I could just replace EVERYTHING ... ... but that could get expensive and might be unnecessary. I will be putting a new compressor, accumulator, and orifice tube on at the least.

Am I correct in my understanding that the rear unit has an expansion tube? Any idea where that would be located? (I haven't done much checking back there yet).

I guess my questions relate to the other items: Evaporator, condenser, clutch fan. Since this van was originally set up to run R12, should I switch to a different type of condenser? Where should I begin evaluating things?

TRB on Sun May 03, 2009 7:10 PM User is offlineView users profile

This has an expansion valve located in the back close to the rear evap core. Condenser is going to be a T & F style, unless you want to go with a universal P & F model and do some hose work. You will have to use the OEM condenser.

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When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

iceman2555 on Sun May 03, 2009 9:52 PM User is offlineView users profile

A good starting point would be to recover what ever refrigerant may be in the system. The secure sufficient amounts of flush to adequately flush and clean the entire system, front evap, all hoses. remove the rear txv and flush the rear evap. Suggest a new rear txv and check the hoses for any cracks or any breaks. Replace or repair as necessary. Since you have already decided to replace the compressor, front orifice tube and accumulator this is a great start.
Not many like the idea of a condenser replacement, but on this vehicle, it is strongly recommended, esp if one wishes the system to perform at its greatest potential. A newer design condenser will offer additional heat transfer and aid in system performance. It may not be necessary to obtain a 'universal' unit, check some of the aftermarket replacements for this vehicle, you may discover that the replacement is the more efficient unit. Just insure that the replacement unit is constructed of aluminum. The brass/copper units do not transfer heat as well.
Install all new o-rings, lubricate with MINERAL oil, not PAGs or POE's.
Install all components, evac and recharge the system. If changing to the more efficient condenser, the recharge rate will probably equal the amount stated for R12. Suggest to use PAG 150 for this system. A double end capped would be the lube of choice.
Insure that the engine cooling system is fully operational. If the fan clutch is over 3 yrs/50k miles, suggest a replacement.
Good luck with your repair.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

TRB on Sun May 03, 2009 10:26 PM User is offlineView users profile

I checked a few national aftermarket vendors and all list a T & F. Only site showing an upgraded condenser is ACDelco. Even that model is just a 6mm piccolo which is only slightly better in my opinion. Since this has an R4 compressor on a dual unit setup. I would make sure I had the best possible heat exchange not only for cooling but durability!

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

iceman2555 on Mon May 04, 2009 9:16 AM User is offlineView users profile

TRB, thanks for the update...and total agreement on the 'max' the cooling...esp on vans...they seem to maintain a tremendous amount of underhood temps.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

Fishermark on Mon May 04, 2009 9:27 AM User is offlineView users profile

Quote
Originally posted by: TRB
I checked a few national aftermarket vendors and all list a T & F. Only site showing an upgraded condenser is ACDelco. Even that model is just a 6mm piccolo which is only slightly better in my opinion. Since this has an R4 compressor on a dual unit setup. I would make sure I had the best possible heat exchange not only for cooling but durability!

In your previous reply, you mentioned that I would probably need to stick with the OEM T&F (I'm not current on some of the abbreviations - does T&F mean "tube and fin" - which is the old style condenser... and P&F mean the newer style which is a parallel condenser?) In your quote above you mention an upgraded 6mm piccolo (again... my ignorance is showing - I don't know what a piccolo is - is there a good post or site for some quick light reading? ).

So I am a little confused - are you saying it would be in my best interest to stick with the OEM style or go with a universal, newer style.

TRB on Mon May 04, 2009 10:17 AM User is offlineView users profile

T & F = Tube & Fin.

If you plan to use R134a I would either see if the 6mm from Delco is available or depending on climate and my preferred choice a universal parallel flow adapting the hoses. This means a little more work and gets away from the OEM look and feel. But it will perform better depending on the size of the replacement condenser.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

Fishermark on Mon May 04, 2009 1:07 PM User is offlineView users profile

Original look doesn't matter to me - and I'm not too concerned about fabbing up some hoses. I currently have the entire front end off of the van as I just replaced the engine and transmission. I am about to begin the process of installing everything back - including the condenser. I live in SW Florida and will be using the van to pull a boat and a camper. I want to make sure the AC works well!

So bottom line, it sounds like a universal parallel flow would be the most efficient choice? What about adapting a condenser from a later model van? Good idea? Bad idea? I am fairly good at adapting things to fit... as long as it physically fits in the opening and works with the system, then I am confident that I can make brackets to get it to work. Again, I just want what will actually work and cool the best.

Edited: Mon May 04, 2009 at 1:09 PM by Fishermark

bohica2xo on Mon May 04, 2009 2:26 PM User is offline

Towing. Florida.

OK, you need the biggest parallel flow condensor that will fit, and couple the air side properly to the heat exchanger stack.

Your fan needs to be working properly, a new fan clutch is recomended. Be sure that all of the air the fan moves passes over all of the heat exchangers. You should be running a large transmission oil cooler. This should be placed second in the stack. Ambient air should pass over the A/C condensor first, then the transmission (and or engine oil cooler if so equipped), and finally the radiator.

An additional electric fan can be used in front of the condensor as a pusher.

B.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Fishermark on Wed May 06, 2009 9:28 AM User is offlineView users profile

Okay, I don't know if this should be in a new post, or continue it here.... but I am ready to order some parts and have a few more questions before I do so:

I have decided to order some items from ACKits, and with each one there is a questions:

1. 15X30 Parallel condenser -- the posts above mention that I will need to do some hose work to make it fit. Does that mean the connectors are a different type, or just that they will probably be in a different place?

2. The chart shows that my van would take 72 ounces of R-12 and 11 ounces of oil. I will be using the DEC PAG 150 and R-134a. Since I am not only changing the refrigerant but also the condenser - how many ounces of R-134a should I use?

3. What is the difference between Nylog blue and red? Which, if either, should I use?

Thanks in advance!

TRB on Wed May 06, 2009 1:47 PM User is offlineView users profile

Quote
Originally posted by: Fishermark
Okay, I don't know if this should be in a new post, or continue it here.... but I am ready to order some parts and have a few more questions before I do so:



I have decided to order some items from ACKits, and with each one there is a questions:



1. 15X30 Parallel condenser -- the posts above mention that I will need to do some hose work to make it fit. Does that mean the connectors are a different type, or just that they will probably be in a different place?



2. The chart shows that my van would take 72 ounces of R-12 and 11 ounces of oil. I will be using the DEC PAG 150 and R-134a. Since I am not only changing the refrigerant but also the condenser - how many ounces of R-134a should I use?



3. What is the difference between Nylog blue and red? Which, if either, should I use?



Thanks in advance!

1. The PF condenser uses a # 8 & # 6 o-ring connection. As for the position compared to OE, they will not be the same thus one reason for a custom hose set.

2. With upgrading the condenser you should be able to get very close to the OEM charge level. Another reason I suggest using this type of condenser!

3. Nylog, red is for r12/mineral oil system and blue is for R134a/PAG & POE systems.



-------------------------
When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

Fishermark on Sat May 16, 2009 4:40 PM User is offlineView users profile

Okay, I have most of the parts I need... but here's a few more questions:

I have physically removed the front and rear evaporators as I wanted to check on their condition. They both appear to be in good shape, with little to no debris on the O-tube. I am replacing the expansion valve in the back and a new O-tube of course. New compressor, new parallel flow condenser, new accumulator. Using the DEC Pag 150.

1. Since the system requires 11 ozs of oil - where do I put it? 3 -4 ozs in the compressor and the rest in the accumulator? (The compressor came with no oil).

2. I have a good set of gauges, and a vacuum pump, but no scale. I only have the little cans of 134a (12 oz cans I believe). Six cans would be 72 ozs. Is that a safe way to go, or would I be better off taking it to a shop for a charge?

3. The only thing I couldn't buy that I wanted to replace was the hose assembly at the compressor. It has a muffler and I have read where they can be difficult to flush - plus I don't know whether it is in good condition. The problem is I cannot find a new hose assembly. No one seems to stock it. What's the best course of action? Have someone cut out the muffler and bypass it? Take the assembly in to a shop for a flush and / or rebuild?

Here's a pic:




Thanks for the help!

[image]http://contentinfo.autozone.com/znetcs/product-info/en/US/rda/34743/image/8/[/image] 

Edited: Sat May 16, 2009 at 4:47 PM by Fishermark

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