• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

AC questions and opinions

Yeah, Hell's Back Porch is June, July August in the Hill Country around Killeen, after any time it rains and the humidity goes to 90% and the temperature hovers around 100°!
 
THEFERMANATOR said:
I don't like those repair kits and the stock 95 condenser was a serpentine capillary ribbon design that was crap for r134 to begin with. I would install a high pressure cutout switch at the condenser and install the purple compressor mounted switch to trigger your evc. 325 psi on and 225 off is a bit on the high side to run your high side pressures. The purple switch closes at 283 and opens at 210. There is also one that closes at 240 but it doesn't open until 150.
Click to expand...


Ferm, what design was the factory 94-95 Suburban? They looked quite a bit different than the trucks. I went ahead and snagged a pair last time I was in the pick and pull yard up near the Idaho farm (3 great pull yards within 40 miles, versus one yard local that is overpriced here in KS, so I hit them whenever I'm out :) ). Looking on Rockauto if a guy was to buy new they are identical PN, but the factory Harrison units are quite different SUV to truck when comparing, both in thickness and tube routing. The fins are coarser as well, which I think would be beneficial to 6.5L cooling.

I dont know shit about the system designs, but my uneducated thought was it would bump system performance slightly on my crew cab 95 that needs a flush anyways ( bad compressor knocking), so I figured I might swap. I grabbed ythe rubber mounts as well, Im hoping the core supports have the same dimensions on the lower rubber mount retainer so it will drop in with no modding.
 
GM Guy said:
Ferm, what design was the factory 94-95 Suburban? They looked quite a bit different than the trucks. I went ahead and snagged a pair last time I was in the pick and pull yard up near the Idaho farm (3 great pull yards within 40 miles, versus one yard local that is overpriced here in KS, so I hit them whenever I'm out :) ). Looking on Rockauto if a guy was to buy new they are identical PN, but the factory Harrison units are quite different SUV to truck when comparing, both in thickness and tube routing. The fins are coarser as well, which I think would be beneficial to 6.5L cooling.

I dont know shit about the system designs, but my uneducated thought was it would bump system performance slightly on my crew cab 95 that needs a flush anyways ( bad compressor knocking), so I figured I might swap. I grabbed ythe rubber mounts as well, Im hoping the core supports have the same dimensions on the lower rubber mount retainer so it will drop in with no modding.
Click to expand...
My 95 Suburban had the serpentine style that used the flat capillary set-up. I know later years went to a parallel flow design as my 99 Tahoe had one in it.

And for the most part, sub's and pickups got the same condensers. GM came to there senses for the gmt800's and put in a bigger condenser for dual air unit than single air units came with.
 
@THEFERMANATOR will a gmt800 dual air condenser fit into our gmt400’s? I’ve been thinking about scavenging our local junkyard soon. Might add that to the list of things to snag lol
 
Forgive me for not knowing squat about a/c systems and trinary switches and whatnot, but I'm a bit confused about where to source a trinary switch and how/ where to install it in a 6.5

In watching the video in the other thread, a trinary switch apparently has 4 wires. Yet both the compressor and condenser switches only have 2 wires each. Are these used combined as the 4 wires of said trinary switch? Does it matter which of the 2 wires going to the compressor and condenser is spliced into? I have the parts for the electric fan clutch conversion and would love to add this feature too, but an electrical novice like me needs a kids- level coloring book diagram for situations like this.

also @THEFERMANATOR , I see you recommend the purple color compressor mounted switch, what color/ pressure parameters do you recommend for the condenser switch? I only see a light green and dark green color switch for the condenser offered on RockAuto (for my '95 at least) and no pressure specs are given for the dark green one
 
DieselAmateur said:
Forgive me for not knowing squat about a/c systems and trinary switches and whatnot, but I'm a bit confused about where to source a trinary switch and how/ where to install it in a 6.5

In watching the video in the other thread, a trinary switch apparently has 4 wires. Yet both the compressor and condenser switches only have 2 wires each. Are these used combined as the 4 wires of said trinary switch? Does it matter which of the 2 wires going to the compressor and condenser is spliced into? I have the parts for the electric fan clutch conversion and would love to add this feature too, but an electrical novice like me needs a kids- level coloring book diagram for situations like this.

also @THEFERMANATOR , I see you recommend the purple color compressor mounted switch, what color/ pressure parameters do you recommend for the condenser switch? I only see a light green and dark green color switch for the condenser offered on RockAuto (for my '95 at least) and no pressure specs are given for the dark green one
Click to expand...
A trinary switch does 3 things, it provides low pressure shut down(opens around 40 psi), it also provides high pressure shutdown (opens around 425-450), and they also provide an output to control electric fans(generally come on around 225-250). 2 wires are for the compressor control and the other 2 are for the fan control.

The condenser mounted switch is a green one, that's it, and it closes around 325 psi, and reopens around 250 psi. The purple compressor mounted switch is generally used for controlling aux electric fans, it closes at 283 and reopens around 210. There is a different compressor mounted switch used for primary electric fan control(don't recall the color off the top of my head right now).
 
Thanks as always for sharing the knowledge Ferm. Is there a schematic anywhere for wiring this? I get the gist of a trinary switch but still have zero clue as how to make it all work on a stock 6.5 setup.

Or is a better question what acts as the binary switch on a stock 6.5 and what needs to be done to make it into a trinary? Not a pressing issue for me at the moment as we're heading into winter here in the northeast and won't need A/C anytime soon, but this is the time when I'll actually have time to wrench and I'll finally get around to the electric fan setup probably sometime in february ahah
 
I looked over the wiring diagram. There is one of the wires that can be hooked to the compressor power wire.
I thought that was for to turn on the fan when the compressor fires up.
Is there a problem with wiring it up that way ?
 
MrMarty51 said:
I looked over the wiring diagram. There is one of the wires that can be hooked to the compressor power wire.
I thought that was for to turn on the fan when the compressor fires up.
Is there a problem with wiring it up that way ?
Click to expand...
Some people wire it so the fan engages with the AC, but this will have your fan clutch locked in solid whenever your compressor is running, and that big fan can draw some power running for no reason. Installing a trinary switch or a high pressure activated switch is a much better option as it will only trigger the fan to lock in when your high side pressure is getting high, and it needs the fan to cool it down. It can save alot of load on your engine, not to mention the noise from the fan locked in for no reason running down the road.
 
DieselAmateur said:
Thanks as always for sharing the knowledge Ferm. Is there a schematic anywhere for wiring this? I get the gist of a trinary switch but still have zero clue as how to make it all work on a stock 6.5 setup.

Or is a better question what acts as the binary switch on a stock 6.5 and what needs to be done to make it into a trinary? Not a pressing issue for me at the moment as we're heading into winter here in the northeast and won't need A/C anytime soon, but this is the time when I'll actually have time to wrench and I'll finally get around to the electric fan setup probably sometime in february ahah
Click to expand...
Each trinary switch uses it's own wiring colors. They normally use 4 wires, 2 for the compressor side, and the other 2 for the fan control side. The factory system didn't use a trinary or even a binary switch. GM installed a high pressure cutout switch on r134 systems in the high side to shut the system off in case the condenser wasn't removing enough heat, a low pressure cycling switch in the low side to cycle the system, and 88-90 and 95+ had a switch in the high side to for e the system to inside air if the high side pressure got above a certain point.

I actually forgot all about the 88-90 systems pressure switch. It is a round compressor mounted style, but it closes and opens at a much lower pressure than the purple one.
 
I have a curiosity since fixing my AC.

I think I had posted what all I did in another thread, but to recap from the beginning of April or so, I ended up leaving my old condenser in since I found out whoever had installed that orifice tube repair kit had welded a different fitting on the end of the line from it going to the evap core. I didn't have access to a replacement line near by without ordering one and waiting another week.

used 105deg + variable orifice tube along with installing a purple fan switch in the compressor since there wasn't any switch mounted there. wired it into the ev fan clutch and away I went.

fast forward to now, I seem to have a slow leak. we had taken a trip to the coast around the beginning of May, about half way into our trip I noticed the ac was beginning to warm up with vent temps close to 60 degrees at highway speeds. once we arrived, I added about 1/2 a can of 134 and that seems to fix that issue.

Today heading home from work I noticed that when I was creeping through the plant ( 5-10 mph) before hitting the road. my fan clutch usually kicks in almost immediately after turning on the ac in the hot afternoons. this time it didn't. it was still cooling with vent temps right at 50 degrees. I also noticed that before I could ever get out on the main road leaving my work, the compressor was already cycling off and on!

So it looks like I may have a slow leak where I'm loosing maybe 1/2 to 1 can worth in about a month. not too bad I guess. looking over all the system this evening the only thing I can see is some slight residue on the high pressure hose from the manifold on the back of the compressor. other than that, everything looks clean and dry for an old dirty engine lol.

this got me to start looking parts up online, manifold suction discharge hose and possibly compressor. I figure I would just keep dumping that little bit of 134A in at least until the leak gets worse or something blows!

looking at RA on compressors they list a few different ones. I noticed "piston" style and "scroll" style. I get what the piston style is but what the ... is a scroll compressor and is it better? I did some duckduckgo searching and see how it's made, but I don't get how it can actually pump lol

the other questions or thoughts I have had on this was stop leak (I have never been a fan of) and also wondering about converting to something like envirosafe freon (propane butane mix that smells like the pine forrest) for this old rig. I have converted older R12 vehicles in the past with good results, but nothing that used 134a from factory.
 
A scroll-style compressor works essentially like the intake side of a turbocharger, except it compresses to much higher pressures. They are used almost exclusively now in home airconditioning systems, as they're highly efficient compared to piston-style compressors.
 
So if I do end up needing to replace the compressor would a scroll style be the way to go? looking at the photos on RA, they are noticeably different.

this is what I have now on my truck...
1654308698763.png
1654308982931.png



and here is what they show as a scroll style...
1654308799464.png

1654309061719.png
 
I am not an A/C expert by any stretch of the imagination, but those appear to both be scroll-type comprsssors, but by different manufacturers. @THEFERMANATOR is our resident A/C and A/C parts exchange expert.
 
You must log in or register to reply here.
Back
Top