Sanden 4440 install

[1998_K1500_Sub]

I read the manual and had to buy an additional bottle of the SP-15 which is 100 viscosity. I flushed the system. I have a total of 10 oz SP-15 in the 68oz R134a system.

My Suburban is a 64oz R134a system with long rear lines (a bit longer than yours I believe). GM says to use 11oz of PAG, and that volume jibes with the Sanden guide’s recommendation.

 

[L31MaxExpress]

My Suburban is a 64oz R134a system with long rear lines (a bit longer than yours I believe). GM says to use 11oz of PAG, and that volume jibes with the Sanden guide’s recommendation.

It may be close but I think my rear lines might actually be longer than the burb. My rear high pressure line start at the passenger front fender, run across the transmission tunnel behind the transmission crossmember, then end up behind the driverside rear wheel well. My rear evaporator is right in front of the rear cargo doors on the driverside. The rear suction line hugs the driverside frame, past the transmission, then runs up over the engine into the rear of the ac manifold. The front suction line on the van is 2x the length of the one on my Tahoe. The oil volume I calculated from Sanden and the OEM volume closely agree. I had a label on my OEM fan shroud that stated to add 1.25 lbs R134a and 2oz PAG with the addition of the old ProAir rear ac. The front only spec was 48 oz and 8 oz pag.

 

[1998_K1500_Sub]

It may be close but I think my rear lines might actually be longer than the burb. My rear high pressure line start at the passenger front fender, run across the transmission tunnel behind the transmission crossmember, then end up behind the driverside rear wheel well. My rear evaporator is right in front of the rear cargo doors on the driverside. The rear suction line hugs the driverside frame, past the transmission, then runs up over the engine into the rear of the ac manifold. The front suction line on the van is 2x the length of the one on my Tahoe. The oil volume I calculated from Sanden and the OEM volume closely agree. I had a label on my OEM fan shroud that stated to add 1.25 lbs R134a and 2oz PAG with the addition of the old ProAir rear ac. The front only spec was 48 oz and 8 oz pag.

Your lines may well be longer, as you suggest. I assumed your rear system was like my Suburban's, e.g,. the lines and other hardware were all on one side of the vehicle (passenger's side, on mine).

I know I've measured my lines' length on the Suburban when I replaced them a few years ago, and used that length in the Sanden formula in their Guide to estimate the amount of oil charge... just to compare the number Sanden provided to that which GM stated in their service manual. It was reassuring to see that the oil oz numbers were similar when determined from different perspectives.

 

[L31MaxExpress]

Your lines may well be longer, as you suggest. I assumed your rear system was like my Suburban's, e.g,. the lines and other hardware were all on one side of the vehicle (passenger's side, on mine).

I know I've measured my lines' length on the Suburban when I replaced them a few years ago, and used that length in the Sanden formula in their Guide to estimate the amount of oil charge... just to compare the number Sanden provided to that which GM stated in their service manual. It was reassuring to see that the oil oz numbers were similar when determined from different perspectives.

I should probably run mine, recover the refrigerant and do the oil level check as they suggest. But the numbers were close and I just ran with it. Using their method with the safety fudge they recomeend I came up with 9.97oz. The add on air plus factory came to 10 oz. I put 10 oz total including the precharge in the compressor and rolled.

 

[1998_K1500_Sub]

I should probably run mine, recover the refrigerant and do the oil level check as they (Sanden) suggest.

I too wanted to run the “oil charge confirmation” steps that Sanden describes in their Guide… but I have no recovery equipment so it costs me 4# of R134a every time I open the system. So like you I just “ran with it”… being as I had two points of reference saying “use 11oz of PAG”. I had some level of confidence.

As an extra-credit exercise I also estimated the additional volume of the rear high pressure line from the Y-split to the rear TXV (easy). Assuming it was completely liquid-filled in normal operation, that gave me a feel for the extra volume of R134a and oil necessary, above and beyond the front-only AC GMT400 systems.

One must then convert the volume of R134a, estimated to fill the line, to oz (weight).

There’s a bit more to the story but I’m sure you get the idea.

I much prefer the MKS system. The possibility of confusing “oz of volume” with “oz of weight” could lead to undesirable results. Terminology such as “cc of oil” and “kg of refrigerant” is much preferred.

 

[L31MaxExpress]

So I ran mine yesterday afternoon with HP Tuners setup to control the idle speed for a perfect 2,000 rpm compressor speed. Shut it off, recovered the refrigerant, drained the oil from the compressor. Ended up adding 1 oz of oil. I took the opportunity to remove the Red ford .062 orifice tube. In its place put a 38902 variable orifice in the front. Then threw it back together, pulled it down to near 30" vacuum for 1 hour. I then recharged it with ~38oz R152a (4 x10oz cans minus the small amount of gas leftover in the cans). I also pulled the radiator while I had it apart after discovering I could sandwhich one of the 16" flexalite fans between the radiator and clutch fan with relative ease. I fabbed some brackets and mounted it. Ran wires to the battery temporarily. In the shop it was ~100°F and 35% humidity. At idle, 850 rpm it is cooling 38°F in the front and 40°F in the rear with both of the blowers on high fan speed. With the 16" fan disconnected at idle the discharge temps are 4-5°F higher, high side pressure is 315-325 and low side about 50-52 psi. With the 16" pulling air, at idle pressures are 290-300 and 40-45. At 2,500 rpm the high side is 340-350 and the low side is 30 psi until the fan clutch locks in and the pressures drop to 315-325 and the low side drops enough to cycle the compressor at 26 psi. I might "recover" a small amount of the R152a and see if I can get the head pressure down a little and improve cooling a little more at idle, but at 2,500 rpm with the van stationary it got down to 31°F out of the vents before the compressor cycled.

40oz of R152a is $17.00.

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[tayto]

l31max, good to see you are still using r152a. i replaced compressor and condenser in my fathers '06 honda pilot and charged it with r152a over a year ago now. now on it's 2nd summer and still blowing cold. do you find the pressures are fairly close to r134a?

 

[L31MaxExpress]

l31max, good to see you are still using r152a. i replaced compressor and condenser in my fathers '06 honda pilot and charged it with r152a over a year ago now. now on it's 2nd summer and still blowing cold. do you find the pressures are fairly close to r134a?

Fairly close to the same with proper charge. I have found it easier to overcharge a R152a system because the capacity is much less. My van is 68 oz R134a and I think I have it slightly overcharged with about 38 oz total in the system. Given that I have a different orifice tube, compressor and condensor my old charge level that worked is off a bit.

 

[1998_K1500_Sub]

Fairly close to the same with proper charge. I have found it easier to overcharge a R152a system because the capacity is much less. My van is 68 oz R134a and I think I have it slightly overcharged with about 38 oz total in the system. Given that I have a different orifice tube, compressor and condensor my old charge level that worked is off a bit.

Is your objective to charge the system with the same volume of refrigerant?

As I know you know, but which some readers may not have recognized, is that the system can only accommodate a certain volume of refrigerant; that is one consideration in the “refrigerant substitution” game.

The density of R134a is 4.25 kg/m³.

That of R152a is 2.7 kg/m³.

So I might assume one would substitute ~40oz of R152a for 64oz of R134a, i.e., scaled by the ratio of their densities.

Comments? I’m learning here, not pontificating.

Next, I assume the orifice tube is selected to provide a similar product for the "mass flow" * "heat of vaporization". I suppose this is practically the same as saying "select the orifice tube to achieve the proper vent temperature" under similar conditions.

Then, the compressor volume per revolution relationship comes into play, but I’ll save that thought.

Note: It may appear I’m mixing-up my dimensions here by scaling the oz (weight) of refrigerant using densities given in terms of kg/m³, but that’s not the case; by dividing one density by the other, the result is a dimensionless scalar. So, the resulting refrigerant amount is still oz (weight).

 

[1998_K1500_Sub]

I have a total of 10 oz SP-15 in the 68oz R134a system.

And later:

So I ran mine yesterday afternoon ... Ended up adding 1 oz of oil.

So that puts you at a total of 11oz (volume) of oil for your 68oz (weight) R134a system, if my math is correct.