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Wintertime AC

Discussion in 'The Garage' started by MaxPF, Dec 19, 2006.

  1. MaxPF

    MaxPF 1/2 ton status

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    Yup, here in the latter part of December I replaced the AC system in my truck. I have a good reason though... while returning from my hunting trip last month my AC compressor siezed, smoking the clutch and breaking the belt. Well, I put the spare belt on (everyone carries a spare belt, right?) and made it the rest of the way home. Well, the smoked clutch overheated the pulley bearing on the compressor, and it was dying. Had that bearing siezed my truck would have ended up on the hook (it has a serp belt setup). So, I decided to fix it now rather than procrastinating and waiting for hot weather.

    Anyone who has done any amount of AC work knows what a POS the R4 compressor is:

    [​IMG]

    They cool fine, but they are HP sucking pigs, they tend to leak around the body seals, and because their lubrication relies entirely on oil carried in the suction gas (they have no oil sump), any low refrigerant or low-flow situation (like short-cycling) will shorten their already limited lifespans. When they blow up they tend to be messy - my sustem was full of metal particles :doah:

    Rather than putting another POS R4 on there (a solution that results in many a K5 getting their AC's completely ripped out :haha:) I opted to put a Zexel TM-15HD in it's place:

    [​IMG]

    The Zexel has mounting ears identical to regular Sanden compressors (which are also good compressors, BTW). The ears actually line up with the mounting holes in the R4 accessory mount. All that is needed are a few new bolts and a couple spacers. These compressors can be had with GM-type manifold pads on them, but I decided to use universal threaded hose ends instead since I was replacing the hoses anyway. You can see that the ends have R134a service ports on them - I elected to use that instead of R12 due to cost and availability.. Since the condenser was full of compressor debris and wasn't efficient enough for R134a I replaced it with a high-density multipass condenser designed for that refrigerant. I also flushed the evaporator and liquid line and replaced the orifice tube and accumulator:

    [​IMG]

    Finally I vacuumed it, charged it, and adjusted the cycling switch to cycle at a slightly lower pressure. Now, 4 hours and $400 later I have a nice, fully functional AC system that I don't even use :haha: At least now I don't have to worry about the AC pulley bearing siezing and leaving me stuck somewhere :D
     
  2. aknight_sa

    aknight_sa 1/2 ton status

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    great job you done there Max!!

    it looks great..
     
  3. cbbr

    cbbr 1 ton status GMOTM Winner

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    Nice. My A/C is a PITA. And is necessary down here.
     
  4. mr.smartass

    mr.smartass 1 ton status Premium Member

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    Cool, wish I had known this a year ago when I slapped another remanned R4 on there... Even when the thing runs right it's still loud as hell... I'll definately look this thread up next time it goes out. Where did you get the compressor from? Next time I do it I'll probably change everything out the way you did as well. How about a quick part list and prices and where you got them from pretty please?
     
  5. 90v1500

    90v1500 Registered Member

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    Yeah, please... I have to replace mine before this summer....:D
     
  6. MaxPF

    MaxPF 1/2 ton status

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    I haven't forgotten abou tthis thread! I need to dig up my parts list for the condenser. However, here's the lowdown. Basically any standard ear-mount Zexel/Seltec/Valeo (they are all the same) or Sanden compressor will work. They are all 134a compressors, although R-12 can be used if the PAG oil is completely drained and replaced with mineral oil. Anyway, you want a Zexel TM-15HD (or equivalent Seltec/Valeo) or Sanden SD7H15 compressor. They are both good units that will give a long life while drawing much less horsepower than an A6 or R4. They are available with a variety of pulleys (6,7,8,10 groove serp or 1 or 2 groove vee belt), so get the one to match your application. You can get them with GM-type manifold pads, but for easiest hose fabrication and hookup I reccomend getting one with standard -10 & -8 threaded connections. For serp setups any 6,7, or 8 will work, but only the first 6 grooves will be used. You will need some 3/8" bolts to hold it in (two 1-1/2" and two 2" long for serp belt setups), as well as some hardened SAE washers, stover lock nuts, and two .312" thick spacers (or a stack of washers). Assembly is straightforward and obvious - just make sure the pulleys line up and that the connections aren't interfered with bu other stuff (that is why I have the compressor rotated nearly 90 degrees toward the passenger side).

    You will need a new accumulator and condenser. If you're sticking with R-12 a stock-type condenser is fine. You can even reuse your existing one as long as it doesn't leak and it is THOROUGHLY flushed. If in doubt, replace it. R134a demands a new condenser because the stocker isn't very efficient. Mine is a multi-pass unit with 6mm tubes that is a drop in replacement for the stock 10mm tubed single-pass unit. A proper one should be labeled "for use with R134a" or somesuch. You also need to replace the orifice tube and have new hoses built. Once done and charged the cycling switch needs to be adjusted to cycle at around 25-28 psi.

    As for where to get the parts, that depends on where you live. Here in the Phoenix metro area you can go to AAPAK or Air Components (that's where I get my AC parts from). Otherwise you need to find a shop that sells nothing but automotive AC stuff - regular auto parts stores ain't gonna have what you need. Do NOT bother getting a rebuilt compressor - The Sandens and Seltecs are cheap enough brand-new (around $225 or so) that you don't want to bother with some rebuilt POS.
     
  7. eagle mark

    eagle mark 1/2 ton status

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    Excellent information as I'm needing to redo my A/C. It does not blow cold and the compressor is making noise when engaged.

    My question to you is will the old r12 style gauges be of any help when doing a 134a conversion? I've seen some at the pawn shop for $25.
     
  8. lectric80

    lectric80 3/4 ton status

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    The gauges for R-12 and R-134a are different, basically the R-134a uses larger connectors. So getting those gauges would be of no use in an R-134a conversion.
     
  9. eagle mark

    eagle mark 1/2 ton status

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    Hmmmm... so would these make them work?
    http://cgi.ebay.com/ebaymotors/R12-...238980941QQcmdZViewItem?hash=item180238980941&
    And do I really need the gauges? I only plan on doing one system but that may change if my 90 Suburban with r12 decides to not work...
     
  10. lectric80

    lectric80 3/4 ton status

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    I would say that you would be better off picking up a cheap set from any auto parts store. Many of their conversion kits include the gauges, and they are about what you would pay by the time you buy the gauges and the conversions for use with the new system.

    You don't neccessarily need the gauges, but it is nice to be able to add refrigerant or check for issues.
     
  11. GreenMonster

    GreenMonster Newbie

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    hey guys...i'm trying to do the r134 conversionon my 91 Blazer. Can you guys tell me where and which connectors are the high and low connectors? Blazer nubee here.
     
  12. MaxPF

    MaxPF 1/2 ton status

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    The low side service fitting is on the accumulator (the aluminum cannister). The high side is on the liquid line, which is mounted to the passenger side inner fender. A 91 will have a late style high-side fitting, which is smaller than the standard low side fitting.
     
  13. eagle mark

    eagle mark 1/2 ton status

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    Thank you. As I researched further I found that to be very true! :D

    :eek1: You've done this before ay... :bow:

    Thanks for the original post, very informative. Could you offer part numbers needed for a 134a conversion on my 1990? Or suggestions? From reading your first post seems it would be the same. We only have parts stores, hose makers up here. No A/C specialty shops like AZ. Good heater shops!! :haha:

    EDIT: A/C was one course I didn't take 28 years ago (ouch!) I found this page to be very helpful in this new project.
    http://www.aircondition.com/tech/categories/A%7B47%7DC-Basics/
     
  14. MaxPF

    MaxPF 1/2 ton status

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    Unfortunately I didn't keep any part numbers. The original post has the part numbers for the compressors. If you don't have AC parts sources in your area I would suggest contacting Air Components or AAPAK here in AZ for the parts.
     
  15. kevin g thompson

    kevin g thompson Newbie

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    I have 94 GMC Suburban with r4 problems. I have looked over Wintertime AC post and think this should also work on mine. Has any other Suburban owners done this? I need to know. There are a few minor differences in set ups from GM trucks. 1) would be breather intake line, 2) would be the 3 line combo set up for the refrigerant line and manifold, and 3) would be my r4 compressor has 2 separate wire connections- 1 single wire one on front, and 1 double wire on rear of compressor. Will same Zexel TM-15HD / Sanden SD 7H15 models work? Thanks guys.
     
  16. MaxPF

    MaxPF 1/2 ton status

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    I'm not sure what you are referring to there. Are you talking about the engine's breather?

    Again, I'm a bit confused by what you are asking. Pics might be helpful :deal:

    The connection on the front is for the clutch. You only need the hot side on the Zexel/Sanden, but the diode located at the connector should be retained. Otherwise, there will be excessive arcing in the clutch relay which will shorten it's life. The easiest thing to do is to cut the bullet connector off the new compressor and replace it with a male blade connector. Then plug that blade into the + side of the clutch connector. If you're not sure which side is which, just pick one and plug it in. If the compressor doesn't cycle on when you have refrigerant in the system, then plug it in the other side. If it still doesn't work, something else is wrong :wink1:

    The plug going into the back of the compressor is a high pressure cutout switch. It is an NC (normally closed) switch that opens when the discharge pressure gets excessively high. Normally, only a malfunction of some type (i.e. bad fan clutch, refrigerant overcharge, blocked condenser) would cause the switch to open. You have two solutions: First, simply bypass the switch by either connecting the two wires together, or removing the switch from the R4 and plugging it in to the connector and then tucking it out of the way somewhere. This is fine for a Zexel, since it has a pressure relief valve. The Sanden may or may not have one - if it doesn't you will have to install one. The second option is to install a high pressure switch in the discharge line. The only complicated thing here is actually getting a suitable switch. Auto AC places usually don't have them, or if they do the cutout pressure is too low (300lbs). You need one that cuts out at 400-450PSI (450 is better if you can find one).

    FWIW, I deleted the HP switch and simply tied the two wires together. I am using a Zexel with a HP relief valve that pops at 450PSI, so I have a "safety" in the event of an overpressure condition. Even on 115 degree days the head pressure on my truck doesn't climb above 300PSI, so no worries :D
     
  17. lectric80

    lectric80 3/4 ton status

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    Number two would be that he has the front and rear AC in the burb, so it has a manifold of sorts for feeding refrigerant to the rear system. It is a little different in the layout, but may not work if there are three lines at the rear of the current compressor.
     
  18. blazin' j

    blazin' j 1/2 ton status

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    sounds like i may need to try this...
     
  19. kevin g thompson

    kevin g thompson Newbie

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    Breather flex hose and assembly routing was what I was wondering. How much of a space issue with a GM H pad? Do we know? It looks like it might be tight spacing. I have VORTEC throttle body spacer to install thats good for 1-1 1/2 inches of found headroom at that area.
    I have an auto ac supplier I found online who is VERY impressed with your little deal.He spent some years as a GM ac tech and at first thought I was #@^&# crazy, until he saw your blog.Now you are a hero, tells me that at all costs to pursue this route as superior to original. He has the compressors at great prices, but had some questions about manifold interfacing.He wanted to know if for manufacturing and/or space reasons that there would be a problem with the 3 line arrangement, and if I could simply have a new one with hoses made at NAPA that would address/adapt to side mounting. Also had questions about cycling switch but I think I got his answer to that from you earlier. Stay tuned....
    For anyone interested, a great source for these compressors which we decided: Models Zexel TM-15 HD or Sanden SD7H15

    Source for these and all else ac: Rick at Auto Air Online 1-800-726-2310
     
  20. MaxPF

    MaxPF 1/2 ton status

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    OK, you're talking about the air cleaner inlet hose, and clearance with a rear air manifold? Well, you can see in my pics how close everything is. The R4 had it's connections on the back. If you can find a replacement with a manifold attachment in the same place you will probably be OK. Otherwise, you will need to weld up special fittings for the conversion. Also, the replacement compressors have less displacement than the R4, so cooling with rear air might be a bit marginal. You definitely want the biggest condenser you can fit. The one I got, while better than the stocker and "designed for R134a", still isn't as good as I would like. My friend has a nearly identical setup in his Jeep, except that he has a condenser from a late-model S-10 (it's a super-efficient parallel-flow type). His AC blows cooler and runs 75-100PSI lower head pressure than mine. I plan on swapping my condenser out for one like his when I do my engine swap.
     

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