My neighbor has a 91 vette. L98 engine..bought it from a dealer. After a week..noticed was running hot in traffic..with a/c. The mechanic said it was the fan on left was gone , and replaced it. then he said the smog pulley , needed replace. Dtill makes a grinding noise..he claimed there was a break in period for the new one? Then the water pump went..replaced that. Now a thousand bucks later..either fan is coming on..Thermo is at 240 or so running at parked idle. A/c compressor bangs on and off hard..causing the engine to almost stall...blowing hot air..and the check gauges come on as the engine almost stalls. Where would i begin to check with the fan problem? relays? a fuse? And is the a/c acting like that cause its low on freon? thanks

 

I would begin by checking the problem with the mechanic, he has issues, and then I would stay out of the B.S cause you're not going to have any fun either.

 

ya..i know what you mean..its my neighbore first vette..ive had a few c4s , but im wondering why the fans arent coming on at all..

 

turn the A/C on , that should start the main one

 

it doesnt..tried that

 

beat feet, it not going to get better

 

okay..lets leave some room for input from somebody that maybe can help..

 

I'm very new at this first offf guys. I just bought a 84 C4 and electrical has never been my strong suit. My fan stopped working last night (ONLY HAVE 1 PULLING FAN) so I installed a new lower temp switch in the head, a 160deg thermostat, and a new fan motor. The fan switch is supposed to kick on around 175-180 and off at 165, the car idled till it was 213 so obviously no power to the fan motor. I checked all the fuses in the panel they where good, plugged the old motor back in in case it was just a bad switch still no power. The volts on my dash read 14.2.......I'm sure this is one of those very simple things if one knows what to look for (which I don't at this point, and feel like a dolt) so here I am begging the help of those who know.......any advice folks I would truely appreciate the help

 

If you put the car into diagnostics mode, paperclip method, when you turn the key on but not start the car the main fan should come on. If not, then most likely is the relay.

Main fan relay on my 88 was on the driver side on the firewall, just behind the wheel but in front of the battery. Mine too was not coming on and turned out it was the main fan relay. This relay is really common throughout the car and only run about $10. If that isn't it, then the fan motor itself could be bad. You could run 12 volts directly to the fan and test it for operation.

With all that work, need to check all the electrical connections are nice and tight too. While installing other things, maybe a connection was left undone.

 

When the AC kicks on, it will jolt the engine a bit. I've seen it act really rough on some cars, some more than others. Check to see if your car has the 10lb frisbee weight on front of the main pulley. That large disk is there to dampen the shudder for when the AC kicks on. Alot of people take them off to increase HP (<10hp/avg gain) and reduce overall weight.

Is the AC ever cold? Put it on max fan, lowest temp (60 degrees) and with the doors open, the AC clutch should run almost continuously. If it doesn't get cold and cycles alot, means you are either low on freon (R12) or compressor is having issues. If low on freon, you'll have to convert it as they don't publicly sell R12 anymore.

Until the fan issue is resolved, I would NOT run the car up to 240 as you are running it dangerously close to its max limits. It would probably have to get up to 260 before it starts spilling its guts but I wouldn't push it.

 

see I didn't even think about the relay or where it might be I checked the connections already I'll run the jumpers in the morning on the fan motor.I tried turning on the key and nothing when I installed everything and in truth am starting to consider a broken wire within the pig-tail coming off of the switch at the head as well. My wiring harness doesn't have a connection for replacement it is wired straight, so I may have to install a female connector for the new pig-tail as well. Thx a bunch for the insight I appreciate it a bunch

 

I would say the mechanic did somthing.

But here is my issue that I had with my 95. The first fan kicks on around 180ish and the other comes on around 2 somthing. They both stoped working and I was reaching temps near 240. The issue was my relay was lose. if I remember correctly it is located near the drivers headlight. I reattached the relay and everything has been fine. I hope you find a solution to the problems. A lot of stuff seems to be breaking at once in that car.

Also make sure the fans are wired in and done correctly. sounds silly but you never know

 

mine is an early build Z51 so unfortunately I only have a single fan for now.......but ya it's a relay, the local Vette shop gave me a relay but it's fualty so I read them the numbers from mine and they are ordering the correct part. After installing the 160 thermostate, new fan, cooler switch,checking fuses, I was pretty stressed elctricity is soooo not my thing. I jumped the connector for the fan and let it idle for 20 minutes in 89deg day heat. Mind you the fan was continuous because of the jumper but the oil was 176 and water temp was 197 so I have high hopes it'll run cool once I get a new relay that works in place

 

Blackthumbs:
I agree with Tony. Make sure that plate is on there. People ignore the A/C compressor a lot since they have improve DRASTICALLY since the 70's and 80's. However, they can slam the car pretty hard. Since it is almost stalling the car, I would say there is excessive drag on the serpentine belt. Start the car, A/C off, and have rev the motor while looking at your tensioner. It should flex when it revs. If it is in it's fully tight position all the time, then you have some very heavy drag on the belt. The A/C compressor itself may be bad, or the AIR that you got may be the issue.
Honestly, it does seem like the common link between all the issues is your mechanic. Try and find a Corvette shop or at least one that deals with Chevy's specifically. Stay away from dealerships!

The code that the car is throwing is probably saying that you have a cylinder missing or something along those lines. My Check Engine light comes on all the time when the motor is warm and idling in neutral. The cam just lubs the car along and the ECM gets angry. It's probably not a real problem and the car is just angry because the RPMs dropped too much.

Newbie 84:
You definately gotta keep an eye on those relays. I got so frustrated, I had my mechanic wire a bypass while he was putting in my new ZZ4 motor (I love that motor so much ). It's a constant on. I'm thinking about wiring in a manual switch, but I worry that I'll leave it off by accident.

 

Good to see you got at least one item figured out. If you are in an area where parts are hard to come by, you may want to order an extra relay; they are common to a couple circuits on vettes so I'm sure you'll get a chance to use it some time in the future.

Run cool!