80 L48

I disconnected the battery while working on my 1980 corvette. Before that all was working fine. Now all of a sudden my air compressor won't come on and the blower motor won't either. Everything else works. Checked fuses, none were blown. Changes a few anyway. Still the same. Not sure if the a/c motor relay is bad and if it is does it control the air compressor. The relay looks original. What to do........

MelWff

the blower doesn't work on any speed? do you have a test light or voltmeter?

80 L48

Blower does not work on any speed. When moving the selector to kick on a/c it does not either. I do have a test light. Before I disconnected the battery all was working. When I hooked the battery back up is when that happened. No air compressor, no blower....

TimAT

IT's a pretty simple circuit- power from the fuse block to the fan switch, then fan switch to the fan resistor and to the fan- HI is the easiest to diagnose- 10ga RED wire from either the junction block or the alternator to the hi blow relay. Here's a print: (It says L82, but the HVAC doesn't care)

https://www.corvetteforum.com/forums...-1980-l82.html

80 L48

[QUOTE=TimAT;1589631287]IT's a pretty simple circuit- power from the fuse block to the fan switch, then fan switch to the fan resistor and to the fan- HI is the easiest to diagnose- 10ga RED wire from either the junction block or the alternator to the hi blow relay. Here's a print: (It says L82, but the HVAC doesn't care)

https://www.corvetteforum.com/forums...-1980-l82.html[/QU

I will try jumping those wires and see what happens. Thank you...

TimAT

Start at the fuse block and work one at a time. Don't hurry, slow and steady. Look at that print and see what does what and then test it. Power from the fuse to the switch, to the resistor, to the motor.

80 L48

Fan switch, relay, and compressor switch are good. All fuses test good. I see 2 metal looking fuses in the fuse box. Don't know what they are. Is there a fuse link anywhere and where is it located? Stumped for now but not giving up. Thank you for the help.

80 L48

[QUOTE=80 L48;1589631922][QUOTE=TimAT;1589631287]IT's a pretty simple circuit- power from the fuse block to the fan switch, then fan switch to the fan resistor and to the fan- HI is the easiest to diagnose- 10ga RED wire from either the junction block or the alternator to the hi blow relay. Here's a print: (It says L82, but the HVAC doesn't care)

https://www.corvetteforum.com/forums...-1980-l82.html[/QU


Tested wires going to resistor, relay, blower motor, and compressor with ignition on using a test light. All tested good. Also jumped wire from orange to purple and then red to purple with ignition on and fan on high and then fan on all settings. I get nothing. Fuses test good with test light with ignition on. On the fuse panel there is a thin plastic box about 4 or 5 inches tall plugged in. Not showing this in the assembly instruction manual. Not sure what it is or if it matters. Out of ideas.

80 L48

Got it working. Black single wire at wiper motor was loose. When following the wires I found 3 black wires soldered together. One going to the blower, one to the compressor and one to the spring loaded switch the hood closes on. When checking wires at starter the black wire connector was broke off which is why there is a home made ground going from wiper motor cover bolt to the frame where hood latch is. Don't understand why compressor and blower motor won't come on when single black wire into wiper motor is unplugged. Looks like a hack job. Does anyone know if the black wire at starter grounds to one of the starter bolts? If so I should be able to do away with home made ground and connect those soldered wires separately. Any help is appreciated. Thank you....

toobroketoretire

Before you start tearing things apart make sure the ground wire that attaches to the blower flange is still tight. Best to put a shake proof washer under the connection before tightening the screw.

toobroketoretire

Hi Tim, I just moved over after things got pretty bad at the other site. Good to see your name again!

80 L48

Have not torn anything apart yet, just troubleshooting and looking at how this thing has been wired. When I plugged in the single black wire at the wiper motor the blower and compressor started working again. Good connections at blower motor and compressor. Tested good with meter. Just curious about these black ground wires being soldered together just before they get to the relay. I don't have a wire diagram but this looks odd. I guess maybe GM ran wires like that back then.

TimAT

The link I posted is a wire diagram. At least that's what GM calls it.

80 L48

I saw that. Thank you for your help.