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mabolzich mabolzich
New User | Posts: 11 | Joined: 08/08
Posted: 08/20/13
09:56 AM

Hi Guys!  I got an 98 C-5 and I'm having trouble with the AC and the heater.  I'm getting no AC and little heat.  The heater core is good.  The AC is full and the compressor seems to be working fine.  The problem, I feel, is in the delivery system.  And don't be telling me to disconnect the battery of pull the fuse.  I've done that dozens of times.  What I'm looking for is a clue and maybe the schematic of the duct system and venting controls.  The blower motor is working fine, it's just that the air doesn't seem to be coming out very strong.  All of this seems to be electronic and I feel that there is a venting duct somewhere that's not opening and/or closing.  The air is going somewhere, just not into the cabin.  Any help would be appreciated.

waynep712222 waynep712222
User | Posts: 129 | Joined: 03/13
Posted: 08/20/13
11:28 AM

see if your AC system accepts commands..

control the system from defrost where it blows air at the windshield.. to the face of the dash discharge to the foot well discharge.. verify it works...

do the same in the different positions with the temp controls..

hot to cold in each position...

there are a bunch of different devices...
and i am not familiar with the C5 HVAC controls.. is your a knob to rotate type.. or a digital push button version.. C4s could be had either way..  RPO label C60 or C68 in a C4...

there is a device called a blend door and it has an actuator.. either vacuum or electrical.. older version used a programmer that moved this lever.. sorry.. i am not familiar with the C5 HVAC..  but they work in similar fashion to the earlier models and all other GM cars and trucks..

i wonder as i don't see any parts listed.. but perhaps these might have a cabin air filter???

if you don't get any reaction from the various actuators...  you could have a vacuum issue or an electrical issue..

take a look at these images...

in this top image..either item 42 or 47 are actuator for the defrost or floor discharge vents..  45 is probably the blend door actuator. . as i recall. another C5 owner found that loose or jammed somehow ..  it will be the one that moves when you change the temp control...

97 02 C5 Evaporatorbox Zpsbef73e0f

number 6 is a vacuum reservoir.  number 10 is a check valve.. #13 comes thru the firewall and is hooked somewhere to the intake or throttle body.. vacuum source for the HVAC.. at the bottom of this image.. you can see the C60 manual control HVAC control head on the right.. and on the left the automatic climate control head. CJ2 instead of C68..  

if you have the CJ2.. you should be able to access the trouble codes either up near the cluster or by pushing and holding the OFF and the WARMER arrow.. then one of the displays will change and codes will start flashing.. turn key off when done.. there is a bunch of stuff in the manual i don't have on this..

97 02 C5hvacvacuum Zps5b1778e2


97 04 C5 Hvacducting Zps7c68ae49

perhaps that will help...  

waynep712222 waynep712222
User | Posts: 129 | Joined: 03/13
Posted: 08/20/13
12:34 PM

i went and reread your post.. this might help more if you have the CJ2 fully automatic temp controls.. Push button not rotary knobs..

i added some of the part names... and i don't know how or if you could change #36 the evaporator filter..

97 02 C5 CJ2 Zps1e781f3f

this should really help  

mabolzich mabolzich
New User | Posts: 11 | Joined: 08/08
Posted: 08/20/13
06:54 PM

Zowey!  This is what I wanted.  I appreciate your help and visual aids.  

waynep712222 waynep712222
User | Posts: 129 | Joined: 03/13
Posted: 08/21/13
05:36 AM

let us know what you find...

i will just be surfing till you come back..

it's getting closer... the light at the end of the tunnel