WHY won't A/C work?!!! Tech doesn't know.

[John Robinson]

Check this for A/C

Check out this vacuum valve.

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[marty.g]

why won't a/c work

robinson were you replying to me or vee93. what does that valve do. i've seen it while looking and replacing old hoses under the hood

 

[marty.g]

I just don't trust the dealers in my area. Last time I took the Vette to them (which I detailed in an earlier post on the CAC) for a simple oil change, they put the wrong weight oil in the car-which I didn't notice until I was balancing my checkbook and looking over the bill. The service manager had the nerve to ask me what I expected them to do about it. Jeez!

So, the Vette is now out in the garage. After 7 muthaf*cking months, it runs. The A/C problem is supposedly fixed, but now that its cold outside, I haven't really bothered to run it for a lengthy amount of time. Before the cold snap here, I did run the A/C on the way home and noticed the 'SYS' blinked for a while. I haven't seen it since, but I really haven't had the time or wherewithall to put the Vette thru its paces yet. The day I brought it home, I later decided to drive it up to warming speed and the d*mn thing wouldn't crank. I charged the battery, drove it around the neighborhood for about 20 minutes then returned to the house and parked it.

When I picked the car up last weekend, I did a walk around. The targa top is scratched, as is an OEM replacement wheel- 1 of 4 I bought off eBay. The shop owner offered to have the scratches buffed out. I told him, no. I will get repair estimates and deduct those amounts from his charges. The passenger door lock cylinder is now broken and the passive key system doesn't snick the doors open when I walk near the car after its sat for a while. The interior lights still do not come on-a direct result of the broken door lock and the malfunctioning alarm system.

The ECM and the HVAC units were replaced. I have them at the house--to be tested later. If I find they are not faulty, I will get my $$$ back.

hope your situation improves. can you help me understand some of the accronyms, such as ecm hvac and what do they have to do with a/c sounds like you and the rest of us need mechanics that deal strickly with vettes. i got a lead from a guy in houston to a guy in virginia i think. the guy in houston works strickly on c5's but the guy on the east works on c4's. the way i came about him i am having a battery drain problem also and he gave me a lead on how to trace the problem. maybe he can point you in the right direction. Bill Curly cell 8608846454 hope this helps.

 

[gmjunkie]

robinson were you replying to me or vee93. what does that valve do. i've seen it while looking and replacing old hoses under the hood

That valve is a Check valve,if it is defective your A/C and Cruse will not work properly!!If your driving and step on the accelerator or start up a Grade the A/C will switch from panel to Default,(start blowing out of defroster and heat vents)if you start up a grade with the Cruse on the cruse will loose vacuum and shut down!! There are other things that can also cause the same symptoms with the A/C, processor under the dash right above accelerator peddle leaking vacuum can cause the same symptoms!! There are a couple threads here on how to repair it,I think 6Shooter posted 1 of them!!I myself have repaired several on 94-96 corvettes!! It's more a Uncomfortable job than hard!! Do a search on C4 A/C you will find them!!

 

[John Robinson]

That valve is a Check valve,if it is defective your A/C and Cruse will not work properly!!If your driving and step on the accelerator start up a Grade the A/C will will switch from panel to Default,(start blowing out of defroster and heat vents)if you start up a grade with the Cruse on the cruse will loose vacuum and shut down!! There are other things that can also cause the same symptoms with the A/C, processor under the dash right above accelerator peddle leaking vacuum can cause the same symptoms!! There are a couple threads here on how to repair it,I think 6Shooter posted 1 of them!!I myself have repaired several on 94-96 corvettes!! It's more a Uncomfortable job than hard!! Do a search on C4 A/C you will find them!!

Thanks Junk I have been all over the FSM and could not find a name for that valve but I knew it provided vacuum to the AC and Cruise. As always you are a step ahead of me.

 

[vee93]

hope your situation improves. can you help me understand some of the accronyms, such as ecm hvac and what do they have to do with a/c sounds like you and the rest of us need mechanics that deal strickly with vettes. i got a lead from a guy in houston to a guy in virginia i think. the guy in houston works strickly on c5's but the guy on the east works on c4's. the way i came about him i am having a battery drain problem also and he gave me a lead on how to trace the problem. maybe he can point you in the right direction. Bill Curly cell 8608846454 hope this helps.

Hey, Marty G.
*HVAC: Heater-Vent-Air Conditioning (add an M on the end for Module)--I just didn't add 'control head unit' to the end in my post. Its the button controlled box for the heater, A/C, defrost, etc.
*ECM: Engine Control Module-the computer for the car
*EEPROM OR EPROM (computer chip)--1. electronically erasable programmable read only memory 2. erasable programmable read only memory

And thanks for B.C.'s #!!! I'll definitely be giving him a call. Right now though, winter has decided to visit Ms. I hate it and am not used to bitter cold--not since I left Iowa over 23 years ago.
So I haven't had the motivation to do much about my Vette of late. Plus, I'm in no mood to have it possibly quit and leave me stranded out in the cold.

 

[vee93]

Thanks, John.
Checked valves and all's well there. Since all that check out, there was a problem traced to the wiring harness and the relay. But that was the tech's fault. The weather should warm up significantly by the end of the week-enough for me to run the A/C and see if I get an 'SYS' light blinking.

I did notice the one green LCD is on on the Heater/A/C control head when I turn the Vette on. I don't remember that being on from the git-go. That could be the trouble there.

Anybody notice if the green LCD is on over the OFF button on the HVAC control head? Thanks, y'all are the best!!!!!

 

[John Robinson]

I did a little research for the valve in my picture. Advance Auto Parts has it listed as Dorman Vacuum Storage: TWO PORT CHECK VALVE: GMThere Part Number is 47150 they list two differant ones under that part number one is under 4 bucks the GM version is $7.99 for that price it is the chepest thing you can replace to be sure the one you have is ok. Incidently I have been having problems with my cruise not holding speed especially on a hill. Thanks to Junks answear I woke up and will replace that valve before I go looking at the more expensive and hard to reach parts. I seem to be having problems remembering to go to the simply things first and not dive into the high dollar parts until they are proven to be bad.;help

 

[gmjunkie]

I did a little research for the valve in my picture. Advance Auto Parts has it listed as Dorman Vacuum Storage: TWO PORT CHECK VALVE: GMThere Part Number is 47150 they list two differant ones under that part number one is under 4 bucks the GM version is $7.99 for that price it is the chepest thing you can replace to be sure the one you have is ok. Incidently I have been having problems with my cruise not holding speed especially on a hill. Thanks to Junks answear I woke up and will replace that valve before I go looking at the more expensive and hard to reach parts. I seem to be having problems remembering to go to the simply things first and not dive into the high dollar parts until they are proven to be bad.;help

It's easy enough to check and see if it is bad John!! Take it off and plug 1 of the two ports on the car side of the valve and a short piece of hose on the other and suck on it!! If you can draw air through that side of the valve,It's Bad!!

 

[John Robinson]

It's easy enough to check and see if it is bad John!! Take it off and plug 1 of the two ports on the car side of the valve and a short piece of hose on the other and suck on it!! If you can draw air through that side of the valve,It's Bad!!

I have been saving clear plastic tubing of all sizes for years waiting for a use for them. I knew they were valuable and now you have told me what I have been saving them all these years for. :duh:blue:

 

[Robertwav1]

I did a little research for the valve in my picture. Advance Auto Parts has it listed as Dorman Vacuum Storage: TWO PORT CHECK VALVE: GMThere Part Number is 47150 they list two differant ones under that part number one is under 4 bucks the GM version is $7.99 for that price it is the chepest thing you can replace to be sure the one you have is ok. Incidently I have been having problems with my cruise not holding speed especially on a hill. Thanks to Junks answear I woke up and will replace that valve before I go looking at the more expensive and hard to reach parts. I seem to be having problems remembering to go to the simply things first and not dive into the high dollar parts until they are proven to be bad.;help

Hey John,
Figured I'd let you know also to check the cables on the ASR motor for the cruise not holding steady. My cable had slipped in the casing, loosening at the TPS. I didn't know until the trans started acting up, not shifting correctly. On our 93's the trans is cable controlled unlike the 94's which are electronic. After doing a repair it fixed the cruise also. I lost the tension one day to avoid somebody running into the back of me. I nailed the throttle so hard the cable loosened affecting the trans. It doesn't cost anything to check. Don't want to get too far from this thread but thought it might well be mentioned.

Hey Vee,
To answer your question on the green LED....Yes, it's lit in the off position. Perhaps diags for CCM might give you some answers with your HVAC if you continue to have a problem when the weather gets a little warmer. Running these pulses all the things inside the car, security light, oil change light, interior light, door locks, fans etc and lets you know if an error occurs.
I actually took apart the LED control to clean it up which was acting erratically. The carbon push buttons clean up nice with some alcohol and a pencil eraser and a little patience. Works like a charm!

 

[John Robinson]

I followed Junks advice and tested the valve. It was fine but when I removed it the plastic vacuum line to the cruise broke off at the rubber connector to the valve. I have made a temp fix and will see if the cruise works. I know this is a bit off the orginal post but not really since that little valve also has some control of the A/C my experience may be the same for others on the A/C side of the valve.

 

[gmjunkie]

I followed Junks advice and tested the valve. It was fine but when I removed it the plastic vacuum line to the cruise broke off at the rubber connector to the valve. I have made a temp fix and will see if the cruise works. I know this is a bit off the orginal post but not really since that little valve also has some control of the A/C my experience may be the same for others on the A/C side of the valve.

Another good place to check John is at the Vacuum reserve tank in behind the front bumper on the Lt front inner wheel shield!! There bad to get a crack in the line there,and also the seam around the tank itself!! I've also had to repair the vacuum Dump lines from the Cruse Unit to the Clutch and Brake peddle switch!!

 

[John Robinson]

The valve did'nt fix the cruise but I now have heat around my feet and the air vents. So what I am saying is to the original poster it's all tied to gether somehow.

 

[XLR8]

Vee, sorry to hear about the problems with your C4. What a PITA!! I don't personally know anyone up your way - but I bet someone in this group could steer you in the direction of a good C4 mechanic.

Mississippi Corvette Club site

I believe they have contact information listed on their site and I would think they'd have a Rolodex full of dependable mechanics, techs and garages between all their members.

Let me know if it pans out.
Jane Ann

 

[vee93]

Vee, sorry to hear about the problems with your C4. What a PITA!! I don't personally know anyone up your way - but I bet someone in this group could steer you in the direction of a good C4 mechanic.

Mississippi Corvette Club site

I believe they have contact information listed on their site and I would think they'd have a Rolodex full of dependable mechanics, techs and garages between all their members.

Let me know if it pans out.
Jane Ann

Thanks, Jane Ann. I'll be seeing MCC members Thursday night at the monthly club meeting. I'm a member. And seeing as how my thread got turned into a Q&A about somebody's valve problem, I'll ask around on other sites also and see if I can get pointed in the right direction.

 

[John Robinson]

PKE Problems

passenger door lock cylinder is now broken and the passive key system doesn't snick the doors open when I walk near the car after its sat for a while. The interior lights still do not come on-a direct result of the broken door lock and the malfunctioning alarm system.

The ECM and the HVAC units were replaced. I have them at the house--to be tested later. If I find they are not faulty, I will get my $$$ back.[/quote]

I just had the same problem with my 93 PKE. The first thing I tried was to replace the battery in the remote. It still would not open the doors. Where I live we have a battery shop that specializes in batteries for everything They tested my remote and said it had a bad signal. Purchased a new remote and programed it and the PKE works now. I also had to replace the fuse for the door locks. As they say you eat an elephant one byte at a time. When I got my new remote I programed it to only open the drivers door the passenger door remains locked. That may get you past your passenger door lock problem temporarily.