A/C compressor replacement

[PlayingWithTBI]

So the original style pressure switch is enough by itself? I think I'm not seeing why the newer one was brought up, and I don't want to damage a brand new system

Does your truck have the "Max" recirculate button? If so, you're good to go. If not, the old 1 wire switch (which is NLA) isn't a good enough safe guard. The A/C is set up to switch to outside air when it gets too high of pressure. The later 2 wire switch and system will turn off the compressor when it sees to high of pressure, protecting your system from spikes and potential blow outs or ruptures (see post #3). I had my high pressure switch blow out of the compressor which ruined the snap ring groove in it so, junk one compressor

R134A runs at higher pressures than the old R12 systems.

 

[351FUN]

Gotcha. Looking back at my order this is the one I have. So I just need to use it and wire it up like your diagram

 

[1998_K1500_Sub]

Gotcha. Looking back at my order this is the one I have. So I just need to use it and wire it up like your diagram

That switch appears to have been used from 1985 up through 1992. In that case, it's R12 specific, and likely will switch at a pressure too low for your soon-to-become R134 application.

You might try looking for a similar switch for a 1995 application. Try looking here:

CHEVROLET > 1995 > K1500 PICKUP > 5.7L V8 > Electrical-Switch & Relay > Refrigerant Pressure Switch

There are a bunch of switches listed there. This one, FOUR SEASONS 35974, has specs that look typical for a high-pressure cut-out function as described by @PlayingWithTBI.

HOWEVER, @PlayingWithTBI (and anybody else reading this), take a look at all the switches listed in RockAuto's catalog at the location I provided. Some are high pressure and some are low pressure. Doesn't (shouldn't) the low-pressure cycling switch act as a low-pressure cut-out? Why do they list both high-pressure and low-pressure cut-out switches, both of which are back-of-compressor mounted? RockAuto isn't always perfect; perhaps some of these switches are appropriate for different years and how each year's AC was wired.

 

[351FUN]

This keeps getting more complicated lol. If I can use the one @PlayingWithTBI linked in post 3 I'll use that, since I can pick it up in store tomorrow.

 

[1998_K1500_Sub]

This keeps getting more complicated lol. If I can use the one @PlayingWithTBI linked in post 3 I'll use that, since I can pick it up in store tomorrow.

Yup, that switch should work. I checked the specs (see link) and the pressures look appropriate.

More Information for FOUR SEASONS 35961

Off Pressure	430
Operate Psi High Off	430
Operate Psi High On	200
Style	High Cut-Out

 

[351FUN]

Awesome, also I response before you added the bit about rock auto and I agree 100%. They list parts that can go there, but not always what is right. I generally use the Vin lookup on the acdelco site to get part numbers, and then find those parts somewhere for sale.

 

[smdk2500]

Should get an orifice tube ADO-15-5378 or comparable from a 99+ too.

What advantages does this orifice give? The A/C works pretty good in my 95 but I wish it would be a little bit colder. I'm also chasing a freeze up problem after running it for 30ish minutes. I don't think a orifice change will help me on the freeze up problem but if it helps it cool better then I am willing to do the work to change it.

 

[PlayingWithTBI]

What advantages does this orifice give? The A/C works pretty good in my 95 but I wish it would be a little bit colder. I'm also chasing a freeze up problem after running it for 30ish minutes. I don't think a orifice change will help me on the freeze up problem but if it helps it cool better then I am willing to do the work to change it.

FWIU the orifice tube for 134A is different than the one for R12. A lot of times freeze up is caused by too low of a charge.

 

[smdk2500]

FWIU the orifice tube for 134A is different than the one for R12. A lot of times freeze up is caused by too low of a charge

Yeah I know freeze up is usally due to low charge. I've weighed it in twice with 2 different scales, put it in based off pressure readings i found somewhere and still no dice. I do know everything is clean in the evap section or if there is anything in there it cant be much. When I had the dash out last year replacing HVAC doors I replaced the evap and cleaned it out. I haven't hooked gauges up yet this year to look at it but it hasn't been warm enough to really need a/c.

I know the orifice tube is different for 134a vs R12 but what made you go with one from a 99+ instead of 94+?

 

[PlayingWithTBI]

I know the orifice tube is different for 134a vs R12 but what made you go with one from a 99+ instead of 94+?

IIRC up to 95 they still had R12. I went with the 99+ because it was readily available at the time.