Project C4, 85 Corvette

[HAULN-SS]

If you get that figured out I'm gonna call in you to help me get my Monte Carlo system up. I bought a 4 seasons compression and got it switched over to r134 but something ain't right about it and I'm a dunce on the subject

[D_Eclipse9916]

Why does this need to be done? What's wrong with the stock system?

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:facepalm:

[Senor_Taylor]

Did C4s not have air conditioning?

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[.RJ]

lulz :?:

[Jake]

Did C4s not have air conditioning?

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No, air conditioning in cars wasn't invented until 1999.



This car has a drivetrain swap, AC never made it in as part of that swap.

[Senor_Taylor]

Did C4s not have air conditioning?

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No, air conditioning in cars wasn't invented until 1999.



This car has a drivetrain swap, AC never made it in as part of that swap.

Thank you. Felt like I was taking crazy pills. This thread was started when I was 11 years old, my apologies for not reading the entire thing.

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[CaptainHenreh]

Did C4s not have air conditioning?

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No, air conditioning in cars wasn't invented until 1999.



This car has a drivetrain swap, AC never made it in as part of that swap.

Thank you. Felt like I was taking crazy pills. This thread was started when I was 11 years old, my apologies for not reading the entire thing.

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Jesus christ, that's true.

OOF. Taylor you want some entertainment go back through some of the old project threads they are amazing. 

Steve, AC was removed when my 442 got surgery, when I do my next engine (yeah yeah) I'd love to put it back, so please document++, thanks, love you, mean it.

[Steve85]

Did C4s not have air conditioning?

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No, air conditioning in cars wasn't invented until 1999.



This car has a drivetrain swap, AC never made it in as part of that swap.

 This thread was started when I was 11 years old

Haha - I was just lamenting about how the carpet is in bad shape and I "just replaced it". This really put it into perspective, I replaced the carpet 16 years ago...

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Steve, AC was removed when my 442 got surgery, when I do my next engine (yeah yeah) I'd love to put it back, so please document++, thanks, love you, mean it.

Definitely will document, trying to have it as a guide for other early C4 owners looking to do a swap and keep the AC functional. There are a couple out there I know of but one hacked up the front K member to use the LS style compressor in its low mount placement and the other was a bit of makeshift brackets and just doesn't seem a long term stable solution with only two bolts holding the compressor in place.

[Steve85]

I got the AC routing worked out and ended up using the orange and blue routing. Trial fit pics are terrible so I'll get better pics with final install. The fittings are a bit different than most crimp style, I went to 5 shops that crimp lines (mostly hydraulic) and responses were either "we can try but no guarantee" to "they don't fit in out tooling". I had to send a bunch of unused fittings back to Nostalgic AC so I sent the lines I made along with the returns for them to crimp. What I also realized is that a lot of these places sell fittings and hose that will work for AC, you just need to use the correct type of O-ring. So if you're doing custom lines (or no longer available replacements) call around, "Collier" is regional supplier and should be a good source. I should get the lines back Mon/Tues and then hopefully get into final install and charging.

I caught a nice break in my search for a crack free top this weekend which I'm super excited about! They are typically anywhere from $600-$1200 to replace. On the low end, that is basically $hipping your top and having a "blem" acrylic lens installed, to the high end GM authentic units. Picked up one from a 92 model off CL for $270 this weekend. I just need to change some mounting brackets to work with the 92 top, those are cheap pieces though readily available.

[Steve85]

TL;DR - AC works!



The full story:

I got the lines back Nostalgic and they looked great, perfectly aligned with my marks and ready to install. I started to second guess whether it had actually been converted to R134 since the fittings for the manifold gauges were not 134 sized fittings and there was a mix of black and green o-rings even though the hoses that were on the car when I bought it were clearly aftermarket and 134 compliant. I started poking around some more and found this blue orifice tube. Apparently, converted GM systems work better with the blue "Ford" orifice tube, there would be no other reason to have a blue one in this car.



Feeling better, I went ahead an oiled up the o-rings and installed all the hoses and the accumulator. Since I never removed the other components from the car (condensor, evaporator) and was careful not ever spill the oil out of the compressor or accumulator, I felt pretty confident I didn't need to add much oil. I added about an ounce to the suction side line (big one on top) for a little insurance though. I decided not to flush the system either since everything was removed in working order. 



get out your big boy wrenches



Looks pretty factory!



Installed the r134 fittings.



Installed and ready to be charged. I picked up some manifold gauges and an air operated vacuum pump from HF for less than the price of one hour of labor for someone else to do it. Of course if you get it wrong and nuke your compressor, gonna wish you paid someone.



The process is pretty well documented in various youtube videos. I watched a couple over and over so I could get the process down in my head. At a very high level, it's pretty straight forward, just need to make sure you're square on which valves to open and close and when. There were couple times during this process some refrigerant spit out (purging) so make sure you have gloves and eye protection!

Wall of text process I followed:

1. Connect hi (red) and low (blue) side fittings to car, open valves.
   
2. Connect vac pump to yellow gauge line
   
3. Open valves on manifold
   
4. Connect air line to vac pump to begin evacuation
   
5. Recommendation is 30 minutes, I did 15 since I didn't flush and my compressor was running constantly to run the vac pump.
   
6. Low side gauge should hit 28-29" of vacuum pretty easily indicating a leak free system.
   
7. Close hi and low valves at the manifold and turn off pump.
   
8. Monitor low side gauge for about 15-30 minutes, there should be almost no loss of vacuum, it definitely should not be dropping steadily.
   

If all good with holding vacuum, continue:

1. Leaving all valves as is, remove vac pump from yellow line and connect to a freon can. (You'll need a valve that goes on the can that pierces the top and has a connector to the yellow line)
   
2. With the can pierced and the valve on the can open, slowly loosen the yellow line at the manifold to purge the line of any air. 
   
3. Start car and set to max AC. (I think this typically engages the cooling fan and/or condensor fan to maximize air through the condensor and keeps the system working it's hardest. If you have a mechanical fan or the max AC feature is not wired up yet, use some other fan pointed at the grill, I used my "Blue Blower". It was interesting that the vent temps where 5 degrees cooler at idle when the my blower was running so it definitely has an impact!)
   
4. SLOWLY open the blue valve at the manifold, freon will begin to flow into the system. (My compressor started cycling on but for very short stints, as more freon got in the system, it stayed engaged longer and longer. The pressure on the low side will cycle at like 45 to 55, and as freon is added the range drops)
   
5. It may be necessary to slowly turn the can horizontal on occasion to get the freon to flow into the system. Not a good idea to turn it upside down quickly and flood the system though. Help it, don't force it.
   

To switch cans - 

1. Close blue valve at manifold
   
2. Slowly disconnect yellow line from can valve (I covered with a rag to prevent any residual spray)
   
3. Put the can valve on a new can
   
4. Connect to the yellow line
   
5. Open the can valve
   
6. Purge the yellow line at the manifold again
   
7. To resume charging the system, slowly open the blue valve at the manifold.
   
8. Repeat until you have added the proper amount of freon (for a conversion, you use 80% of the recommended R12. My car calls for 44oz of R12, I put 34oz of r143. It should take 35.2, but I went with 2 11oz cans and a 12 oz can for a close enough. I already had 3 11oz cans, which is why I didn't do 2x12 +11)
   
9. Monitor vent temps and low side pressures. (novice advice here, my high side gauge stayed at 0, not sure why but the system was operating so it had to be something with my valve positions. I was so worried about "DON'T OPEN THE HIGH SIDE" that I didn't mess with it. Also, all those recharge kits in the store ignore the high side.)
   
10. Vent temps should down in the low 40s
    
11. Low side pressure should cycle 30ish to 45ish (Exact pressures depend on a lot of factors but almost every video I've seen and my own experience, is in this range)
    

To stop charging - 

1. Close the valve on the freon can
   
2. Close the valves at the fittings attached to the car
   
3. Close the manifold valves
   
4. Disconnect the valves from the car
   
5. Remove the can from the yellow line (might be some leakage here, use caution)
   
6. Open all the valves on the gauges to purge everything (I really didn't get much, if anything, coming out)
   

That was about it! 

Some tidbits I learned along the way:

• r134 hates being overcharged, too much in the system will reduce performance
  
• A blue orifice valve is a good idea for a GM system converted from r12 to r134, especially if performance is poor at idle/slow speeds.
  
• It's just a process like anything else, not sure why I waited so long.
  
• If rewiring the compressor, it definitely needs a solid ground.
  
• The amount of air being pulled across the condenser has a big impact on system performance. If you've installed a smaller fan, an underdrive pulley (mechanical fan) or anything that would reduce this airflow, it will impact the temps you get from the vents.
  
• This old compressor takes a PAG 150 oil for use in a r134 system. I did see some caution around using PAG in a conversion that it can react with left over chlorine in an old r12 system. Mys system was open so long and previously converted so I went with PAG 150 with UV dye. If you're doing a conversion ona GM car, safest bet is a GM oil designed specifically for this. It's discontinued but still available through Amazon.
  
• If the compressor exploded and spewed it's guts through the system, then flushing is a must! If you don't know why the AC was removed, probably a good idea to flush and see if you get metal particulate. If so, you need a new accumulator and orifice tube at a minimum. Try to flush the heck out of the evaporator and condenser because the freon will just pull it all back to the compressor and explode the new one. A new condenser if fairly cheap, might be advisable insurance.
  

Pics
Gauges showing a good seal after 30 minutes


blower set up



Vent temp progress as I was adding freon







YEEEEESSSS!



sweatin it out



Low side pressure cycling




To do yet:
Compressor is juuuust hitting hood support, so need to cut some of that away
Clean up compressor wiring
Wire max AC setting to cooling fan

Very happy with what I learned along the way, how it turned out so far and looking forward to driving it whenever.

If anyone needs ACsistance or some gauges to borrow, let me know!

[HAULN-SS]

Does your car have vacuum for the vent doors and shit? That mess of tubes behind the dash intimidated me as well last time I was looking into this. We might have to arrange a Saturday meet up sometime!

[Steve85]

Does your car have vacuum for the vent doors and shit? That mess of tubes behind the dash intimidated me as well last time I was looking into this. We might have to arrange a Saturday meet up sometime!

It does and it doesn't work perfectly but I have it where I get air from the main dash vents and from the defrost so the heat, AC and defrost all function. At least as well as any 35 year old vacuum system can be expected without a total overhaul. I need to reinstall my vacuum storage ball and see if I can get things moving like they are supposed to.

One of the things I learned on these older systems is that they are really very simple. The head unit controls all the blend doors with vacuum but that is all separate from the very simple control of the compressor clutch. Even if the vacuum lines that control the blend doors are complete toast, the compressor only cares whether the slider is one of the AC positions. If so, it gets 12v when the pressure switches say so and it makes cold air.

Yeah, I'd be happy to meet up sometime!

[Steve85]

TL;DR - It worked, then it didn't, and now it does again.

After having the AC work great in the driveway for 3 days I decided to take it out a couple weeks ago and AC stopped working before I even go to the bottom of the driveway. Not cool.

The difference was disconnecting the trickle charger, it was providing just enough juice to make up the difference from a low voltage problem to keep the compressor clutch engaged. After driving it a few miles to get gas it also gave me a chance to double check for leaks and it seems every internal compressor o-ring gave up. Oil was on the clutch shaft, seeping out between the body and shell, and anywhere else it had an o-ring. Not a surprise I guess, old, old compressor. (Very odd that it did wait for me to drive it though, was clean in the driveway...)

 

Ordered and installed a new compressor from Rock Auto. As is often the case, my car had a compressor that was only used for a couple years so of course even the new ones are a slightly different style. The main difference is the how the suction/high pressure manifold mounts to the compressor but I had enough leeway in the hoses that everything fit.

I had to go through the whole vac and recharge process again and so far so good. I also had to trim out some of the under hood bracing since the compressor sits a little higher than stock. Compressor bracket and upper hose were hitting the hood occasionally and it caused a few leaks. Once cleared and tightened up, no more hitting and no more leaks. (probably need to top off some refrigerant though)

I mentioned above needing to wire the fan and that is crucial too. In all my freon charging and testing, I had my shop fan blowing in the front. When I started the car without it, the AC would not cool until the engine warmed up and the main cooling fan came on pulling air through the condenser. This was originally controlled by the ECM that gets an "AC on" signal through a pressure switch and runs the cooling fan. Since I have two fans, the main cooling fan and a pusher fan in front of the radiator and condenser, I wired the pusher to run as long as 1) AC was selected in the control head and 2) the switch that spoke to the ECM now just directly grounds the pusher fan relay. 

Today was a great test day with full sun and temps in the 90s. Had a bit of a hiccup yet with the low voltage issue at start-up but I cruised for about 30 minutes in mixed conditions, some stop lights and cruising anywhere from 35 to 65 and the vent temp was a solid 42 degrees! Even with 42 degrees at the vent, with full sun and no tint, it had to work hard to maintain comfortable temps in the car. 

I need to clean up some wiring, figure out this low voltage thing, top off the refrigerant and I should be good to go.

I think next will be redoing the interior which is really just a few pieces of carpet and some new seat covers. Not doing red again (at least not carpet), the sun wrecked it in no time, been reading that red is the worst for that.

[Senor_Taylor]

What page do I need to go to in order to see some photos of this thing?

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[HAULN-SS]

You keep that car parked outside?

[Steve85]

What page do I need to go to in order to see some photos of this thing?

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Reposting since photobucket is complete trash, how it currently sits:



Damn I miss the BBS RKs, should find the buyer and see if he wants to sell them back...

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It does sit outside and we are in some sort of wind tunnel here that blows the cover off so I don't always have it on. Been slowly but surely making room in the garage so I probably won't do much with the interior until I know I can protect it. Driving it more would mean more sitting out exposed anyway so I'll want the tint and rear cargo cover installed.

[JPolen01]

Can't go wrong with BBS or CCW. The CCWs are ballin'.

[Senor_Taylor]

The wheels on the bottom are ABSOLUTELY HOT.

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[Jake]

The BBS wheels are killer, Steve. You need those again.