Sanden AC compressor for Suburban with front and rear air

[haromaster87]

Hey everyone, this question is specific to those with a Suburban equipped with front and rear AC that they've switched to R134a with a Sanden AC compressor. What model/part number compressor did you end up using? And how well did it perform for both the front and rear AC set up?

The AC in my 1990 Suburban was non functional when I got it so I gathered up the components to revamp the system and switch it to R134a. Since the current pancake compressor was already kaput, I looked into upgrade options and came by the numerous recommendations for a Sanden AC compressor, so I ended up with an SD7H15.

I haven't actually started the repair/upgrade yet, but the other day I saw a discussion for someone with the same dual AC setup that had switched to the same Sanden compressor and he couldn't get it to cool below 60*. Based on the thread, I think he had other circumstances causing his issue. But in that discussion, a user mentioned the Sanden SD7H15 is not a large enough displacement compressor for a system with front and rear AC and that it's best suited for front AC only.

There wasn't much elaboration beyond that, but it got me looking and I found the SD7H15 indeed only displaces 155cc, whereas the R4 in the dual air Burbs was supposed to be a 180cc unit. On paper, it does seem inadequate. But I have found various mentions of folks using the SD7H15 on their G series vans with dual air and having excellent results. So I'm curious if any one has any first hand experience with a SD7H15 on a dual air Suburban and how well it worked in your local climate. Thanks for any info!

 

[gmbellew]

this is what I am running in my dual air 1990. with a good fitting shroud, good clutch fan and a small pusher I run with AC on attached to my trans cooler i have no complaints at all. been running it for 4 or 5 years now.

if the truck has been sitting in the sun it takes a while to overcome the heat soak of all the metal in the vehicle. but if it has been in the shade, I can be cooled down quick.

no issues maintaining the cab comfortable in upper 90s and humid with recirculation (Max) on and moderate blower speeds. I do have tinted windows, though....I am sure that helps a little.

New Sanden Style 4864 AC Compressor - Auto Air Online

New Sanden style 4864 ear mount ac compressor complete with 12-volt clutch, 119MM 8/ groove pulley, and single wire male Packard connector with diode.

www.autoaironline.com

 

[YakkoWarner]

This is a topic I need to follow closely since I have effectively the same problem - 1989 with front and rear air, system pretty much dead although it will get slightly below ambient air temp but not much. I have the orig. style R4 compressor and want to go with a Sanden style because the R4 is REALLY noisy which makes me suspect its not long for this world.

I'm trying to figure out exactly what has to be changed (I'm assuming dryer/accumulator, compressor mounting brackets, orifice tube, condensor and hose fittings at the compressor). Is there any kind of kit that contains all the needed peices or at the very least a list of what parts to buy?

 

[gmbellew]

This is a topic I need to follow closely since I have effectively the same problem - 1989 with front and rear air, system pretty much dead although it will get slightly below ambient air temp but not much. I have the orig. style R4 compressor and want to go with a Sanden style because the R4 is REALLY noisy which makes me suspect its not long for this world.

I'm trying to figure out exactly what has to be changed (I'm assuming dryer/accumulator, compressor mounting brackets, orifice tube, condensor and hose fittings at the compressor). Is there any kind of kit that contains all the needed peices or at the very least a list of what parts to buy?

Dryer and orifice tube for sure. The compressor I linked above works with stock hoses. Condenser is your call, really. Make sure the fan shroud is tight to the radiator to maximize fan performance at idle and low speed. Flush the system good. Pull the rear TXV to make sure it isn’t plugged up. Flush everything out really well.

 

[dd1990]

On my 90 Burb I went Sanden compressor and Parallel flow condenser, by burb is an icebox when I have the ac running.

 

[winfred]

on my sanden swap into a 91 350 burb with an r4, most of the dirty dingo adaptor crap didn't work, but i am uniquely equipped to build ac lines and fab brackets, i just didn't wanna and tried the retail option, biggest annoyance was the compressor back plate that was supposed to accept the stock manifold hose assy, would not, it's been more than 10 years, so, maybe the sanden chineseum adapters suck less these days

 

[Hunter79764]

That compressor should be enough for you. Definitely make sure the lines are clean, replace orifice and think about cleaning or replacing the TXV in the back. A parallel flow condenser will improve performance if you're worried about it and replacing it anyway, I'd recommend it, especially for Florida heat and a Suburban.

Definitely need a new drier any time the system is opened up for any length of time, you may need to adjust the low side cycling switch pressure to get the best cooling without freezing up, although if you buy a new one, it is probably already at the 134 setting, a little over 20-22 psi.

If you want the short version, that's it, stop reading. If you want to get everything out of it that you can, keep reading...
Do some looking at orifice colors and make a choice, white is factory I think, and will work. Blue (step smaller) should be better, especially with a modern compressor and condenser that can handle higher pressures. Red is another step smaller from there. Higher pressure will be less efficient and "harder" on the overall system, but will transfer more heat and probably not much of a practical downside for a fun truck. Make sure you have good airflow, either a good functioning clutch or good electric fans, I prefer OEM's vs aftermarket. They were designed much better, as long as you can make them fit right. If you aren't sure about the airflow etc and don't want to mess with it, white will be safest. If you have good airflow, changing it up makes a better choice, depending on pressures.

Your charge will be completely new, i.e., once you change components from stock, the old rules of thumb are out the window. They might get you close, and might be close enough, but if you want it right, you need to get a set of gauges, a scale, and charge it to pressures you like. Low side pressures will determine how cold your evaporator is, colder evap will cool and dehumidify better but will be more prone to freezing over in intermediate conditions. You pressure cycling switch determines when the compressor kicks on and off, and should be set to not allow it to pull pressure too low, helping with the freeze over issue. But actual charge levels will control the low side "running" pressure, more charge is higher pressure. Check google or ai chatbots to help set your low side for your actual ambient conditions, keeping an eye on your high side pressure that it recommends. Higher high side pressure will make "more cold", but will push closer to unsafe pressures in high outdoor temps, high engine speeds, and high loads etc. Lower high side pressure limits system capacity, which is why going to a blue or red orifice may help overall capacity. If both pressures are low, add more charge. If both are high, you put in too much. If the low is high and the high is low (too small of a difference), get a smaller orifice, if low is too low and high is too high (too much difference), check for obstructions and go a step bigger on orifice size. And let me know which one you land on, I need to do the system on my 87 and would love to copy your homework and save myself from pulling charge to swap orifices

 

[YakkoWarner]

Icebox is definately what I want down here in Texas for sure - I know the mounting position of the factory compressor is frequently different between small block and big block vehicles - I'm trying to figure out if there is a specific bracket (or brackets) to buy that will let me use a Sanden style unit on a big block, or am I going to have to find a custom fab shop? I don't have the ability to make custom hoses so being able to use stock specification hoses would be ideal.

 

[skysurfer]

Sanden 4864 (SD7H15HD-FLX) is what I put in my 89. Not plug and play, but I figured it out despite knowing nothing about AC.