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Killing a Compressor

Trikebent on Thu July 25, 2013 8:41 PM User is offline

Year: 1989
Make: Mazda
Model: B2200
Engine Size: 2.2L
Refrigerant Type: R134
Ambient Temp: 100°F
Pressure Low: 40-50
Pressure High: 300325
Country of Origin: United States

Long post!
Original R12 system with no pressure in it. Factory sticker under hood lists capacity of 28 oz R12. The old compressor appeared to be original Sanden 708. Given the age and appearance, I didn’t even check it; I just pulled the compressor and all components. No sign of catastrophic compressor failure. Old oil was med-light brown color. No debris found anywhere in system during disassembly.
I flushed condenser (OEM serpentine style), evaporator and hard-lines individually. To clean evap & condenser used deodorized mineral spirits, then final flush with acetone. Blow thru test into clean white paper towels both wet & dry showed no discoloration or solid debris. Hard lines flushed with brake cleaner. I was obsessive about cleanliness. After cleaning/drying, I capped/covered all connections.
Re-assembly: New Alpha Compressor, new expansion valve, new receiver/dryer, new barrier hoses with all new fittings were made with R134 service ports approx 4“ from suction/discharge ports on compressor. All new O-rings (green R134a compatible) When assembling used I used BVA O-ring lube (purchased at local auto A/C shop) on O-rings and Nylog on threads.
Assemble evap with new expansion valve, then pressurized evap assembly with filtered air at 85 PSI. Submerged pressurized evap in water for 10 minutes to check for bubbles, did same procedure on condenser. Both were leak tight.
Added 2 oz oil (PAG 46 with dye) to receiver/ dryer, did not drain or change oil in compressor. I left the factory caps on the compressor ports until the last minute at assembly. There was oil at the discharge port when connected the lines to the compressor. Note: compressor has vertical ports. Due to mounting issue, compressor was mounted with ports at approx 45° from straight up. Using gage set, both valves open, and a 3 CFM, 2 stage, vacuum pump, evacuated to 30 in hg for 45 minutes. With valves closed and pump off, allowed to sit overnight and saw no decrease in vacuum.
Connected 12oz can R134 to gage set, purged air out of line. Put gas R134 into system thru both low & high pressure ports to obtain approx 70 psi. Closed valves on gage system held pressure overnight. Here is where I think I made my first mistake. (Strike 1) I then started the vehicle. I charged R 134 gas into the low side port. I put in 1 can over a period of 5-10 minutes, changed cans and put in a partial 2nd can. I did not use a scale. (DUH!) I think I wound up over charging. I was watching the low side pressures not watching both low & high pressures. Pressure went as high as 350- 370! psi. on the high side and was at 40-55 on low. Air Temperatures 2” in front of the condenser were about 105°F deg when I did this. Vent temps went briefly as low as 65°F and then stabilized at 70°F.
I then drove the vehicle in this condition using the AC for approx 4 hours. Vent temps were 60-70 deg with outside temps in the 90’s. After doing more research on this forum, I realized I was likely overcharged. I then had the R134 recovered from the system and found that there was only 5-6 oz in the system.(Strike 2)
I then removed all components & re-flushed/cleaned per previous procedure. Oil appeared clean. No solid debris/discoloration. Found a cracked fitting on the condenser. I replaced the condenser with an OEM serpentine style. I added 4 oz oil to inlet on compressor, 1.5 oz to receiver/dryer. I re-assembled, evacuated, etc. per above. This time I turned compressor by hand 12 turns in normal direction.
Connected 12oz can R134 to gage set, purged air out of line. Using a digital scale this time, I put in approx 2 oz. gas R134 into system thru both low & high pressure ports to obtain approx 70 psi. I then closed valves on gage. System held pressure overnight. I also checked all fittings using Rectorleak solution at this time. I don't have a electronic leak detector.
Here is where I think I did myself in again.(Strike 3) I started the engine, turned on the A/C and slowly add R134, 1-2 oz at a time using the scale. It took me approx 1 hour to add 19 oz of R134 to the system. (using the sticker of 28 oz R 12 I should add 21 oz R134) At a temperature of approx 90-95°F, with 15% RH, 1500 RPM, I was getting 30-40 PSI low/ 225-250 high, vent temps of 55°-60°F with fan on high, no recirculation.
This seemed pretty good, I’d rather be on the low side that overcharged, so I stopped there.
A test drive lasting approx 20 minutes showed 50°-60° vent temps on a 100°F/15% RH day on mixed city/Freeway driving. Best temps were on the Freeway (of course). I was very happy with the results. A few days later I drove the truck for 5 hours on the Freeway in 100°F conditions. Seeing vent temps ranging from 45° to 55°F depending on fan speed. I was real happy. I did not note any compressor cycling. I am assuming that due to the warm temperatures and the lower efficiencies of R134 I am not getting the evap down to freezing and tripping the freeze switch.
The truck was parked for 2 days. On day 3 the truck was driven using the A/C, vent temps were in the 45°-55° range for approx 1 hour with outside temps 85°-90°F’s, then I stopped and parked for about 30 minutes. After restarting the truck to continue home, when the A/C was turned on, I got a loud belt squeal. I thought the belt was loose, but instead the compressor was seized. As a result I drove 5 hours in 100 deg temps without A/C.
At home, had the R134 recovered, approx 19 oz out. I then removed all components from vehicle. No sign of oil found externally on any components. I drained oil from compressor as best I could since I could not rotate the compressor, only about 2-3 teaspoons came out the ports. I also removed the top & bottom plugs from the compressor to drain and look for evidence of damage. No discoloration or debris found. Condenser, receiver/dryer, evaporator, & lines produced approx 2 oz oil out. No sign of debris or discolored oil found.

Mistakes made (I think) that killed the compressor
•On the initial install, I don’t remember if I rotated the compressor by hand to distribute the oil.
•On the initial install, overcharged R134, maybe oil as well.
•On 2nd try at charging, added R134 too slowly, compressor may have been oil starved due to lack of R134 to circulate oil. I may have had this issue on the 1st try as well.

•Did I do something else wrong?
•On an Alpha compressor, is the inlet the correct place to add new oil?
•Is running the Alpha 45° off vertical OK?
•Is 11-12 oz of a 21 oz charge enough to circulate the oil and prevent oil starvation?
•Should I rotate the compressor by hand after putting in the initial 11-12 oz charge?
•Should I see compressor cycling/evap freezing with the conditions I have?

Next time
When charging the next time, with the engine off, I plan on getting as much of the 1st can in as a liquid (can inverted) thru the high side to start with. I will not put liquid thru the low side at any time.
Anything else I should do different?

webbch on Thu July 25, 2013 8:56 PM User is offlineView users profile

You already have a scale? Get a 30lb cylinder of R-134a and save yourself such headaches with the cans! Not sure what a cylinder of 134 is going for these days, but less than $130 I'd imagine. I can't help with why the compressor died. Seems like you were pretty thorough on the install - would've surprised me as well.

WyrTwister on Thu July 25, 2013 9:23 PM User is offlineView users profile

I do not know for certain , but I would stop all the flushing , especially with all the non traditional fluids . If you are going to flush , do it with fluids made for that purpose .

I am not saying I am right or wrong , but with late 1990's and early 2000's GM cars , I pull the vacuum . Let the vacuum set to see if all is OK .

I then start the car , get the refrigerant hooked up to the hoses & lines purged . Turn on the A/C . Compressor " pressure switch " does not allow the clutch to pull in . I then shoot liquid R134a into the system , to get enough refrigerant in to all the clutch to function .

I am pretty sure the liquid is going into the accumulator ?

I continue to charge with R134a until the charge is complete , keeping an eye on temps and pressures .

I bought a 25 pound cylinder at Sam's for some where around $ 80 + tax . I had been paying about $ 10 + tax for 12 oz cans at Walley World .

God bless

bigkev on Fri July 26, 2013 1:49 AM User is offline

You really overcharged it (bad for compressor) and then the next time you for some odd reason decided to fill it up over an hours time (bad for the compresor). For the oil you can just spread it out as you put the system together, put a couple ounces in different components until you reach your total. Ive even filled them by sucking the oil into the gauge hoses with a vac pump, or they even make oil injectors that go inline with your gauges. You will probably get a million suggestions here but its really quite simple, put the oil and r134 in by weight and don't think so much into it. I don't know if it makes a difference how you mount that compressor, maybe someone else here does, Why get a compressor that doesn't match anyways?

Cussboy on Fri July 26, 2013 2:53 PM User is offline

I've got a rebult Air Pro Sanden 708 compressor on my 1988 B2200 truck, and it's done great (with R-12) for the past decade here in Arizonz heat. The compressor, and the replacement evaporator (leak, a year before that, maybe I didn't add back enough oil that time), came from AMA board sponsor here.

Trikebent on Fri July 26, 2013 7:21 PM User is offline

A rebuilt compressor was not shown on the website & I was advised to use the Alpha. I was needing new hoses and converting to 134 so using the Alpha universal made sense at the time. I bought all parts from the forum sponsor based mostly on recommendations on another forum. I don't feel I have a warranty claim due to the overcharge and slow fill, so I'm putting in a new replacement at my expense. I just want to do everything right this time. This is only the 2nd time I've been into a an AC system. I've learned a lot. I'm looking at the replacement cost of the compressor as my "Tuition"cost. Even buying 2 compressors I'm still way less cost than having taken it to a commercial shop.

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