Rear A/C oddities

[iamdub]

I fixed my A/C tonight but noticed the rear A/C is still quirky. When set on "face", it blows out the headliner vents but isn't cool at all. It's not full-on heat, but not chilled. When I switched it to "feet", the air from the vents under the seats is cool. I didn't let it run long enough to see if it would get as cold as that coming out the dash vents, but it was definitely cooler than that coming out of the headliner vents.


The aluminum lines underneath the body at the right rear weren't cool at all. Shouldn't they be?

Also, the rear climate control panel seems to be doing strange things. When any button is pressed, it'll show the full display of temp, fan speed and vent selection. After about five seconds, the duct selection part goes away. It'll come back and respond accordingly if you press the button to cycle through the options. Pic with it missing:

After about 10 seconds, the whole display goes blank except for this:

 

[89Suburban]

I read that there should be a rear orifice tube in one of those rear lines back there somewhere.

 

[swathdiver]

Seems wonky to me. Did you ever buy a Tech-2?

 

[gpracer1]

Im pretty sure its an expansion valve in the rear.

 

[iamdub]

Seems wonky to me. Did you ever buy a Tech-2?

*sigh*

No. And I hope this isn't "that time". I've kept it in the back of my mind that I'll get one if/when I get to the point of absolutely needing one. I've been able to get by just fine so far. But, now, do I make this possibly $100 repair a $400+ (somewhat arbitrary figures) repair by adding in the cost of a Tech2? I feel that most anything else I'd have to mess with on this thing can be diagnosed "manually" or with the help of HPT. What's more of a kicker is that the rear A/C isn't even much of a needed function for me.

 

[iamdub]

I read that there should be a rear orifice tube in one of those rear lines back there somewhere.

Im pretty sure its an expansion valve in the rear.

Regardless of which it has, would/could this be my problem?

I'm not in a huge rush to get into deep diagnostics with it yet. Just fishing for ideas. I'm thinking I should start with the control panel since it appears there's a definite problem there.

 

[gpracer1]

With the AC on the rear evaporator is either going to be cold or not. If cold then probably an air flow issue. If its not cold it could be expansion valve, maybe the sense tube came out of the clip or its bad.
This is assuming correct charge and compressor is ok.

 

[George B]

Try a new Delco control on RA and see what happens.

 

[swathdiver]

*sigh*

No. And I hope this isn't "that time". I've kept it in the back of my mind that I'll get one if/when I get to the point of absolutely needing one. I've been able to get by just fine so far. But, now, do I make this possibly $100 repair a $400+ (somewhat arbitrary figures) repair by adding in the cost of a Tech2? I feel that most anything else I'd have to mess with on this thing can be diagnosed "manually" or with the help of HPT. What's more of a kicker is that the rear A/C isn't even much of a needed function for me.

Well, when is the next time you're taking that thing to Florida?

 

[George B]

According to our Tech2 owners sheet Ivan74 is in Houston. Thats the closest I can find to New Iberia LA. I was supposed to be in Sulphur LA next month but plans changed.

 

[iamdub]

With the AC on the rear evaporator is either going to be cold or not.

So, with the normal/front AC on, the rear evaporator is included in the loop, so it should be cool as well? I didn't think there was a valve to isolate the flow of refrigerant from the rest of the system when the rear AC was turned off.

If cold then probably an air flow issue. If its not cold it could be expansion valve, maybe the sense tube came out of the clip or its bad.
This is assuming correct charge and compressor is ok.

Sense tube? I'm assuming the charge is ok and compressor is in working order since the front AC is doing great. I'll have to check the evaporator directly.

 

[iamdub]

Try a new Delco control on RA and see what happens.

I kinda feel this is at least one of the problems. Do you know if this will need to be programmed?

 

[iamdub]

Well, when is the next time you're taking that thing to Florida?

I'll be there in November for my cousin's wedding. Not sure if I'll be down any time before then. Really, I'm not even sure I'll drive. I'd like to drive down for a long trip with no real agenda so I'd have the freedom to roam.

 

[iamdub]

According to our Tech2 owners sheet Ivan74 is in Houston. Thats the closest I can find to New Iberia LA. I was supposed to be in Sulphur LA next month but plans changed.

I was just in New Iberia last week for work. I could make a weekend trip to Houston. I have family around there. Actually, they just spent the weekend here and we all were at my brother's house yesterday. Plenty to consider here...

 

[swathdiver]

I'll be there in November for my cousin's wedding. Not sure if I'll be down any time before then. Really, I'm not even sure I'll drive. I'd like to drive down for a long trip with no real agenda so I'd have the freedom to roam.

For all you spend in fuel to get to Florida or Houston, just order one already! LOL Or get one of those MDI2 adapters with GDS2 software and use it with a laptop so you can use it on more modern GM stuff.

 

[George B]

For all you spend in fuel to get to Florida or Houston, just order one already! LOL Or get one of those MDI2 adapters with GDS2 software and use it with a laptop so you can use it on more modern GM stuff.

^This^

 

[iamdub]

For all you spend in fuel to get to Florida or Houston, just order one already! LOL Or get one of those MDI2 adapters with GDS2 software and use it with a laptop so you can use it on more modern GM stuff.

LOL
Well, I wouldn't drive to Florida or even Houston JUST to borrow a Tech 2. I'd go to visit fam and just work in a quick rendezvous with someone that had one as a side trip.

Unless I looked up the wrong thing, it looks like the MDI 2 is around $200. If I got that and download the software to a laptop, would I have all the same functions as the Tech 2 plus the ability to use it on more modern vehicles? Unless there's something I'm missing, it just seems like a waste to spend ~$100 more on the Tech 2 and have more limitations. Pretty much anyone has or can get a cheap laptop to dedicate to this cause. I feel I'm misunderstanding something.

 

[swathdiver]

LOL
Well, I wouldn't drive to Florida or even Houston JUST to borrow a Tech 2. I'd go to visit fam and just work in a quick rendezvous with someone that had one as a side trip.

Unless I looked up the wrong thing, it looks like the MDI 2 is around $200. If I got that and download the software to a laptop, would I have all the same functions as the Tech 2 plus the ability to use it on more modern vehicles? Unless there's something I'm missing, it just seems like a waste to spend ~$100 more on the Tech 2 and have more limitations. Pretty much anyone has or can get a cheap laptop to dedicate to this cause. I feel I'm misunderstanding something.

I will someday get the MDI2 but find the Tech-2 handier to use while on the road compared with a laptop.

 

[iamdub]

I will someday get the MDI2 but find the Tech-2 handier to use while on the road compared with a laptop.

So that's the only considerable difference other than a wider range of vehicles- convenience of an all-in-one package? I have a dedicated laptop for HPT. It'd make good sense for me to add the MDI 2 functionality to it. Between that, the HPT scanner and my Autel recording live data of any selected PID(s), I should be covered whether I'm parked and activating modules or datalogging while moving for drivability diagnostics.

I'm not trying to skirt around getting a Tech 2 as much as I'm trying to use what I already have and gain what I don't for just ~$200. I could get some velcro straps to be fancy and hang the Autel on the steering wheel like the Tech 2.

 

[swathdiver]

So that's the only considerable difference other than a wider range of vehicles- convenience of an all-in-one package? I have a dedicated laptop for HPT. It'd make good sense for me to add the MDI 2 functionality to it. Between that, the HPT scanner and my Autel recording live data of any selected PID(s), I should be covered whether I'm parked and activating modules or datalogging while moving for drivability diagnostics.

I'm not trying to skirt around getting a Tech 2 as much as I'm trying to use what I already have and gain what I don't for just ~$200. I could get some velcro straps to be fancy and hang the Autel on the steering wheel like the Tech 2.

That'll work, just check with ACDelco's TDS system to make sure the laptop is up to their standards in case you need to program.