Is Sanden swap worth it? 88 K1500

[OLD BLUE 88]

I'm the original owner of this truck. It's not a show piece, but my go to for runs to the dump, etc. Over the decades, the most replaced part has been the R4 compressor. Could be the techs that did the install used lesser quality remans or off brand new units. The last one was supposed to be a quality compressor, it lasted 2 years. I plan on doing this job myself and hope not to do it again. I'm an old man. What'aya think?

Cheers!

 

[1998_K1500_Sub]

I’ll assume your AC has been converted to R134a.

It has been said the R4 is susceptible to leaks.

The R4 may have worked well in the R12 era of lower "high-side" pressures, but R134a operates at much higher pressures.

I believe the old '88 AC systems may not have a high-pressure cut-out switch on them to disable the compressor. If so, and unless you've added one (as some some others have), your high-side pressures may become excessive. @PlayingWithTBI might comment.

So, IMHO:

- check for the presence of a high-pressure cut-out switch and, if missing, install one

- consider the Sanden as an upgrade

- some on GMT400 have installed the third-party "scroll" compressor that's housed in an R4-sized case; it's an easy swap with some favorable results reported. I believe these can still be found on RockAuto at a reasonable price.

Managing the high-side pressures is important regardless of compressor…

- the old tube-and-fin condensers from the R12 era aren't optimal for R134a as they don’t transfer heat as effectively; “replacement” is an upgrade path to consider.

- improving the airflow through the condenser will help manage high-side pressures. Much has been discussed on GMT400 on this topic; see posts in various threads by @L31MaxExpress.

 

[OLD BLUE 88]

Great advice, thanks!
The condensor was updated when the last R4 was installed.
I'll double check the high pressure switch.
The scroll compressor in an R4 type case may be a good idea.

I'm planning on a restoration at some point. At such time, I can pull the dash and do a total retro fit with one of the AC systems with a new control system and ducts, etc.

Thanks again

 

[Caman96]

I thought @L31MaxExpress wasn’t impressed at all with the Sanden.

 

[Vikingdude]

I don't have first hand experience, but it sounds like the compressor that gets your vehicle colder, faster is 4 seasons, 10 cylinder HT6 style, PN 88947. I would also refer to @L31MaxExpress and his extensive writeups on ac systems and maximizing output in the hot Texas summers.

 

[PlayingWithTBI]

I plan on doing this job myself and hope not to do it again

When you do, will you replace the Condenser, Orifice tube, and receiver/Dryer as well as the pump? You can't completely flush the Condenser, it'll still have some junk from the blown compressor in it, as well as the Orifice Tube. Flush the rest of the system before assembly.

When you get the pump, empty all the oil and measure it. Your system probably calls for ~8oz of PAG 46 or 100 (whatever). Put 4 oz in the compressor, turn it by hand to spread it around, preventing a slug going through it on startup. Make sure you have the 2-wire HP Cut off Switch in the back of it.Then put the other 4 oz in the Receiver/Dryer. If you only have 1 wire going to that old switch, ground it to the T-Stat housing and wire the new switch in series with the LP Cycling Switch. The old wire, when grounded will open the Recirc Door for inside air after 30 seconds when, the A/C is on its lowest setting and the fan is on 2 or 3. Here's a little drawing of how I did my 88. I also wired in a relay so I get full battery voltage at the Compressor Coil too. It shows (OEM) Cut Off at ~25 PSI

You must be registered for see images attach

Your Cycling Low Pressure Switch probably has an adjusting screw between the connector blades on your 88 but, if not, get one so you can lower the pressure shut off to ~20 PSI (i have mine set to 18). I'm getting ~35° (from my R4) with a 98° ambient temp. @L31MaxExpress gets even colder air with another refrigerant.

Suck the system down to ~-28 or more " (a perfect vacuum is ~29") for about 1/2 hour or more, shut off the compressor, close the valves on your manifold Gauges, and let it sit for a while - I prefer overnight. Check to see if it maintained the around same vacuum. Then add refrigerant per manufacturer's recommendation (remember it takes less R134a), I usually use 3 cans, until you get it putting out ~20+ PSI @100° (my recommendation). Your high side s/b lower this way and still give you cold air.

Phew, sorry for the dissertation.

 

[1998_K1500_Sub]

... it sounds like the compressor that gets your vehicle colder, faster is 4 seasons, 10 cylinder HT6 style, PN 88947

^^^ Problem: HT6-style compressors are not the easiest retrofit for the R4. Too, for @OLD BLUE 88's pickup, the big 4-Seasons compressor isn't so important; for large vehicles (Tahoes, Suburbans), it is.

I thought @L31MaxExpress wasn’t impressed at all with the Sanden.

@L31MaxExpress wasn't impressed with the Sanden HT6 replacement (Sanden p/n 4440, 4261) and it was IIRC in the context of a dual-evaporator system; the Sanden had less pumping capacity (cc/rev) than the OE HT6 and was far below that of the 4-Seasons 10-cylinder HT6. Pumping capacity, for a dual system, is a concern.

Regarding the R4, the Sanden replacement model often used is p/n 4864.

@Wildblue19 has used the Sanden 4864. Search for his posts in this thread:

88-94 5.7 Suburban A/C Diagnosis and Tuning

Hey everyone. Unique A/C question on orifice tubes for my 1993 GMC 5.7 4x4 Suburban. TLDR, AC sucks and I took off my condensor lines and there was no orifice tube - straight up empty pipe. Put one in and negligible changes in vent temps. Is having no orifice tube intentional for rear air...

www.gmt400.com

I don't remember @L31MaxExpress noting a concern about, or having experience with, the Sanden 4864.

See the attached .pdf for the Sanden 4864 This unit has no obvious provision for a compressor-mounted high-pressure cutoff switch like the HT6 compressors do; see my notes within. @Wildblue19 probably dealt with this, somehow.

Unique mounting brackets (available via third-parties, eBay, etc.) are required. See attached pdf.

 

[1998_K1500_Sub]

Considering the simplicity of the retrofit, and assuming @OLD BLUE 88 has a regular-cab pickup, I would be inclined to try the scroll-style replacement compressor.

I'm tired of leaking R4s and would rather try something different.

On RockAuto, see

GPD 6511351 ~$200

UAC CO11168MAC