Install A Complete A/c System?

Caver Dave · April 7, 2010

'99 Suburban 2500 with RPO code YG6 (HVAC SYSTEM AIR CONDITIONING, NOT DESIRED). Since it's primarily a work truck (purchased as towrig & general hauler), it's not a *real* high priority...

However, it sure would be nice for occasional family trips (requiring lot's of gear) & during the SE's 90*+ weather!

My main questions:

- Are the wiring/connectors still included in the harness?

- Are the under dash "plenums" (air box containing heater/AC cores)?

- A brief look left me guesstimating that it might be missing firewall holes for the additional lines? (appears to only have a small hole just large enough for heater core & drain currently)

If so, theoretically I could add the compressor (the compressor bracket is installed)/condenser/core/lines/etc, swap the HVAC control panel, have it charged and be good to go? I realize that it may require a semi-total dismantle of the dash & plenum also.

jro909 · April 7, 2010

should be able to, its would be alot of work though...putting the compressor in and running the belts and the clutch...let alone the switches...i'd recommend the 2w55mph system...its less stressful

Caver Dave · April 7, 2010

should be able to, its would be alot of work though...putting the compressor in and running the belts and the clutch...let alone the switches...

That's funny! All the things you named are the EASY parts! That stuff bolts in/on with minimal stress and the switches should just plug/play (pending confirmation of harness capabilities)...

Pulling & opening up the airbox appears to the real work!

i'd recommend the 2w55mph system...its less stressful

I'm fine with to a certain point. Probably about time the sweat starts running down the crack of me arse (the vinyl seats will aid here

) after a long, hot day... I'll be ready for more than just circulating the hot air around the interior "convection oven" fashion!

Spurshot · April 7, 2010

I'm sure anything is possible, given enough time, money and effort. I'm betting it's gonna be a project and then some. Given that it's 11 yrs old, would selling it and buying something with A/C be in your budget?

Caver Dave · April 8, 2010

Given that it's 11 yrs old, would selling it and buying something with A/C be in your budget?

While purchasing a "new" (AC'd) truck is well within my financial means, I'm hard pressed justifying a $500+ payment & insurance... given it's intended purpose:

- to haul a 6500# trailer & Jeep once a month (maybe less frequently),

- haul an occasional hay bale/bag of feed or Jeep parts

- backup family hauler/3rd vehicle

- less than 6K miles/year (combined total)... spending the majority of it's remaining life "parked & waiting" in the back

Not to mention the vinyl interior (easier cleanup) and "1 payment plan" (got it for what I believe was a steal) making it *THE* correct vehicle... I figured the parts could be sourced from a JY as opposed to purchasing new to keep the entire thing "lowbuck" (no need to double the cost of the vehicle adding options!)

Besides, don't we all "need" a couple projects?

nickvrebel · April 8, 2010

first off - I'm from S. Louisiana, I have never heard of a vehicle that didn't come with A/C lol

I don't have any direct knowledge of this swap, but my thought:

something that may be of concern, but I'm unsure....

In fuel injected vehicles (I know this is true at least for GEN III+ V8s) the tune has certain parameters that are a/c dependent.

the differences are minor and possibly there by default, but there is that chance that it is not. PCMwise this will only affect the vehicle really when sitting at idle with A/C on, but it may or may not be much of an issue if it does.

ways to solve this:

possible need to reflash BCM/ PCM or get otherwise equivalent from salvage yard.

You state that this is a 1999, the 1999 model SUV's still used the 350 V8 correct? (which would make it a GEN II V8).

I would say the first thing you need to explore is if the harness is behind the current heater control. If it is the swap may be real straight forward, move on to the fuse panel and see if the backside of the fuse block is wired for the various fuses. Also look at the compressor's mounting point and look for the harness for the compressor clutch and high/ low pressure switches.

I think you are taking the right approach going to a salvage yard looking for a donor vehicle, some parts may simply not be available (perhaps a partial harness) from the dealer.

Caver Dave · April 9, 2010

first off - I'm from S. Louisiana, I have never heard of a vehicle that didn't come with A/C

Was a bit shocked there was a factory option to delete it myself! My uncle (former Pontiac/Buick/GMC dealer) called it a "price vehicle"

In fuel injected vehicles (I know this is true at least for GEN III+ V8s) the tune has certain parameters that are a/c dependent.
the differences are minor and possibly there by default, but there is that chance that it is not. PCMwise this will only affect the vehicle really when sitting at idle with A/C on, but it may or may not be much of an issue if it does. ways to solve this: possible need to reflash BCM/ PCM or get otherwise equivalent from salvage yard.

Thank you sir... that was something I hadn't thought of!

I'm decently versed in the TBI stuff (converted my '72 Jeep Commando w/ AMC304 to TBI using GM parts & starting the conversion on my brothers '84 CJ-7 w/ 258 I-6), so your right about the "AC" parameters. On the 1227747 (TBI) ECMs, 12V from the compressor clutch being engergised, is applied to an input that raises the idle by/to "X" amount. Maybe I'll luck up on BCM/PCM from the AC donor!

You state that this is a 1999, the 1999 model SUV's still used the 350 V8 correct? (which would make it a GEN II V8).
I would say the first thing you need to explore is if the harness is behind the current heater control. If it is the swap may be real straight forward, move on to the fuse panel and see if the backside of the fuse block is wired for the various fuses. Also look at the compressor's mounting point and look for the harness for the compressor clutch and high/ low pressure switches.

I think you are taking the right approach going to a salvage yard looking for a donor vehicle, some parts may simply not be available (perhaps a partial harness) from the dealer.

Correct. The VIN is definitely '99 and it is a 5.7L.

After pulling the bezel earlier this week to troubleshoot some dead/intermittent cluster lamps, it won't take much to check for additional pigtails behind the HVAC block (*should've* checked when it was already apart!). However, I'm guessing it may be in the harness already connected, just not pinned in the HVAC control?

If I understand correctly, you're saying to confirm there are actually connectors to receive fuses, rather than "blank" holes/slots? That'd be a shame!

I took a quick looksee the other day, but didn't see anything that looked like the compressors feed... but it highly possible those connections are bundled up in the loom (didn't go that far)...

nickvrebel · April 9, 2010

the tune won't be a big deal most likely.... I had major trouble adjusting it when I was tuning a truck that we swapped in a 6.0L with a large cam (into a 2000 1500 Silverado), to keep the a/c working at idle was tricky tune wise b/c of the cam.... but for your application, if it bogs the motor at idle then just shut off the compressor until you are moving again, not too bad. Also there is a feature called "stall saver" in the tune that will abandon all parasitic loss to the motor to keep the motor running at all costs, such as killing the compressor

If I understand correctly, you're saying to confirm there are actually connectors to receive fuses, rather than "blank" holes/slots? That'd be a shame! biggrin.gif
I took a quick looksee the other day, but didn't see anything that looked like the compressors feed... but it highly possible those connections are bundled up in the loom (didn't go that far)...

correct

I'm not saying one way or the other, but the reason why I suggested this as a possible bump in the road is this:

On my 2003 Silverado LS I did not have fog lamps from the factory.

I bought the kit to retrofit it with from GM. The wiring was there already for the switch and in the dash, however it fed to a fuse that was missing the wire on the other side - the kit included a harness that needed to be added to the bottom side of the fuse panel and run to the actual lights.

Knowing that - there is a possibility that some or all of the harness needed may be missing, you'll need to look closely between a donor vehicle and yours to determine what you will need. Either way, you should be able to do the retrofit, but it will definitely be more than a one day project.

Good luck!

Caver Dave · April 21, 2010

I'm not saying one way or the other, but the reason why I suggested this as a possible bump in the road is this:
On my 2003 Silverado LS I did not have fog lamps from the factory.

I bought the kit to retrofit it with from GM. The wiring was there already for the switch and in the dash, however it fed to a fuse that was missing the wire on the other side - the kit included a harness that needed to be added to the bottom side of the fuse panel and run to the actual lights.

Knowing that - there is a possibility that some or all of the harness needed may be missing, you'll need to look closely between a donor vehicle and yours to determine what you will need. Either way, you should be able to do the retrofit, but it will definitely be more than a one day project.

Well, you're correct Nick!

The "under hood" fuse block is missing the wiring/harness for the AC relay/fuse and the pigtail for the engine side appears to be non-existent... not exactly a show stopper, but adds to the complexity/PITA factor a bit!

OTOH, the wiring for adding Cruise Control appears to all be there & waiting... picking up the turn/wiper/CC stalk & CC module this evening.