hvac no communication
Thread Starter
Advanced
Joined: Aug 2000
Posts: 75
Likes: 6
From: Senoia, GA
hvac no communication
my 97 HVAC digital control head works intermittently comes on after the car has been running for 15 mins and than goes off the dic code is 99 no comm has anyone seen this before?
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The HVAC heads have a well known issue with poor solder joints. That is the very first thing to check. Disassenvle it and look for poor solder joints. The lighting resistors ae the first to come loose but you may have poor connectibs in other locations. Just resolder each component. If your not solder savvy, take it to a TV repair place and see if they will look at it for you.
Tech Contributor
Joined: Jan 2007
Posts: 19,341
Likes: 1,121
From: Dyer, IN
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
As strange as it sounds,,, Open BOTH doors,,,,,grab the rubber accordion tube between each door and shake the crap out if it and see if that changes things.
BC
BC
Tech Contributor
Joined: Jan 2007
Posts: 19,341
Likes: 1,121
From: Dyer, IN
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
Thread Starter
Advanced
Joined: Aug 2000
Posts: 75
Likes: 6
From: Senoia, GA
other codes
PCM 0134h, 135c, 138c, 154h, 161c, 1571h, TCS 1281H, RTD no comm, BCM 0532H, IPC no codes, Radio 1018H, HVAC no comm, LDCM no codes, RDCM no codes, SCM B2606, RPA 1096H, 1064H, 1016H
PCM 0134h, 135c, 138c, 154h, 161c, 1571h, TCS 1281H, RTD no comm, BCM 0532H, IPC no codes, Radio 1018H, HVAC no comm, LDCM no codes, RDCM no codes, SCM B2606, RPA 1096H, 1064H, 1016H
Tech Contributor
Joined: Jan 2007
Posts: 19,341
Likes: 1,121
From: Dyer, IN
http://forums.corvetteforum.com/c5-t...ch-repair.html
Le Mans Master
Joined: Aug 2000
Posts: 6,273
Likes: 14
From: Austin TX
Tech Contributor
Joined: Jan 2007
Posts: 19,341
Likes: 1,121
From: Dyer, IN
I think what Bill is referring to is the class 2 wiring within the doors. I certainly cannot compete with Bill's years of experience on the C5; however, there are a few issues in conjunction with the OP's A/C control panel going dead, that lead me to believe the ignition switch is suspect.....namely the P1571 code in conjunction with the A/C issue. Below is a similar situation:
http://forums.corvetteforum.com/c5-t...in-common.html
http://forums.corvetteforum.com/c5-t...in-common.html
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Lucky is correct on more than one point. The class II serial buss can effect different modules in different ways. Its possible for a shorted serial buss (in the door wiring harness) to effect a specific module.
As for the ignition switch, if the voltage coming out of the switch is LOW due to poor contact inside the switch, all the modules supplied by the voltage out of that switch will or could possibly have issues.
Read the Hot is Run and Start 12 VDC voltage/fuse for that module and make sure its the same as battery voltage.
The serial buss and the ignition switch are BOTH well known C5 problem areas.
BC
As for the ignition switch, if the voltage coming out of the switch is LOW due to poor contact inside the switch, all the modules supplied by the voltage out of that switch will or could possibly have issues.
Read the Hot is Run and Start 12 VDC voltage/fuse for that module and make sure its the same as battery voltage.
The serial buss and the ignition switch are BOTH well known C5 problem areas.
BC
Thread Starter
Advanced
Joined: Aug 2000
Posts: 75
Likes: 6
From: Senoia, GA
thanks for the help. purchased a new ignition switch and replaced, now the car will not start when ii turn the key to start nothing happens, and the steering column is locked and i cannot unlock it??
Intermediate
Joined: May 2024
Posts: 25
Likes: 0
The HVAC heads have a well known issue with poor solder joints. That is the very first thing to check. Disassenvle it and look for poor solder joints. The lighting resistors ae the first to come loose but you may have poor connectibs in other locations. Just resolder each component. If your not solder savvy, take it to a TV repair place and see if they will look at it for you.
could this Linked with having no AC
Tech Contributor
Joined: Jan 2007
Posts: 19,341
Likes: 1,121
From: Dyer, IN
Intermediate
Joined: May 2024
Posts: 25
Likes: 0
meaning, I’ve tried replacing all the relays. I’ve replaced the head unit and I’ve also checked to see if the compressor was still running and it runs when I jump it with a probe, but it doesn’t turn on when I click the AC button and it starts to blink and for some reason, the scanner tool that I use says that the HVAC system isn’t connecting to the tool to read any codes and on the built-in code reader for my car. It says that there’s nothing that pops up on the HVAC, not a history or a current code and I’ve also tried to jump it with a probe with the fuse box that’s underneath, the passenger side foot rest with the dark green wire that didn’t work and my mechanic is tested the pressure sensors for the air conditioning lines and says that they’re completely fine But been searching over the Internet and still can’t find anything what’s wrong with it?
