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92 S10 Truck Blows Air Out Floor Vent Only
Posted: Sun Jul 28, 2019 4:26 am
by Dgreen
Just converted this truck for a friend. Ac hasn’t worked in many years from the looks of things. Changed the compressor, accumulator, orifice tube, and added 6 oz pag 150. Pressures are good and lots of water coming from the evaporator, but air blowing in the cab is in the upper 60s and only blows out the floor vent.
Re: 92 S10 Truck Blows Air Out Floor Vent Only
Posted: Sun Jul 28, 2019 4:31 am
by Dougflas
Vacuum line is bad. Is this a 4.3 engine? Common problem.
Re: 92 S10 Truck Blows Air Out Floor Vent Only
Posted: Sun Jul 28, 2019 11:32 am
by Dgreen
It’s a 2.8 liter.
Any particular line or just start checking all the vacuum lines I can locate?
Re: 92 S10 Truck Blows Air Out Floor Vent Only
Posted: Sun Jul 28, 2019 11:36 am
by Dgreen
Also seems to be a lot of chatter from the clutch. I set the gap at .030. Is that too much?
Re: 92 S10 Truck Blows Air Out Floor Vent Only
Posted: Sun Jul 28, 2019 5:06 pm
by Dgreen
I adjusted the clutch gap down to .022 and it seemed to be less noisy. Took the covers off the underside if the dash. Pretty sure I can hear a vacuum leak, but can’t tell which direction it’s coming from.
Re: 92 S10 Truck Blows Air Out Floor Vent Only
Posted: Mon Jul 29, 2019 8:03 am
by bohica2xo
Set the clutch gap as tight as you can without drag. .015 is good, it only wears bigger. .030 gap is too wide.
Locate the vacuum reservoir under the hood. It should have a line from the manifold, and one to the firewall. Trace the firewall line from the cab side of the firewall. If nothing is working the failure is in the main source line.
Reservoirs crack as well. Check the underhood lines and the plastic tank.
Re: 92 S10 Truck Blows Air Out Floor Vent Only
Posted: Tue Jul 30, 2019 11:14 am
by Dgreen
The rotary vacuum switch on the AC and heater control is leaking. No luck finding one locally so far.
Re: 92 S10 Truck Blows Air Out Floor Vent Only
Posted: Tue Jul 30, 2019 1:48 pm
by Dgreen
I had some success! Greased up the vacuum control switch with silicone grease and reinstalled. We have cold air blowing out the vents! The metallic noise is still there. Only when the clutch is engaged. I took the hub and hub plate off and didn’t see any problems. Reinstalled the clutch and set to .015. Would a bad bearing make a noise only when the clutch is engaged? Also, I had to change the coil when I first started this project so the plug on he coil would match the style that is on the truck. Donor compressor is from an older model.
Re: 92 S10 Truck Blows Air Out Floor Vent Only
Posted: Wed Jul 31, 2019 5:54 pm
by bohica2xo
Pull the belt off & check the pulley bearing. Try to rock the pulley. If it rocks, or feels rough, the bearing is on it's way out.
When the clutch engages it can pull a bad bearing in to a different location where it makes more noise.
Re: 92 S10 Truck Blows Air Out Floor Vent Only
Posted: Thu Aug 01, 2019 3:03 am
by Dgreen
Well, I changed the bearing and still have a noise. Also tried a different hub plate. Only thing I haven’t tried is a different coil and pulley. I put a stethoscope on the compressor and it sounds good.
Is it possible that the coil is weak and letting the clutch to slip and causing it to make noise?