Anti-dieseling relay question???

[Critter]

Can someone give me an explanation of what this thing does? I am troubleshooting my blower fan and ran into this relay on the diagram. Where is it physically located in my 72 Blazer? I ran a search but couldn't find any details. By the way, I jumped the fan itself to the battery and it spins fine, but somewhere between the switch, the blower relay, and this thing, I guess power is lost.

[Critter]

Well, I have since found this diagram and learned the function of the anti-dieseling relay. Still I am confused on where this thing is and if my truck has it. Was it a year model change?

[Jtrux]

Just sell your blazer and buy one that works.

[Bentblazer]

I have a similar relay that runs over and attaches to the air box near heater coil. It mounted near the top not far from the pass, side vent. Not sure if it is the same thing your looking at though.

[Critter]

Originally Posted by Bentblazer

I have a similar relay that runs over and attaches to the air box near heater coil. It mounted near the top not far from the pass, side vent. Not sure if it is the same thing your looking at though.

That's the blower motor relay that is in the upper right corner of both diagrams. I'm assuming they are similar but there is a different number of wires running to them.

[BobbyK]

It's function is to keep the A/C compressor engaged after you turn off the truck. works like a "brake".

If you need the compressor to engage to stop dieseling you've got other problems.

[BLUE THUNDER]

I'm with Jtrux, just sell it dude.

[old man jimmy]

The 72 with Q-jet carb. came with an anti-dieseling selonid, that was just a plunger afair on the carb linkage. That when you turned the key off, it dropped the idle lower to stop it from deseling. But didn't know it had a relay. Mine's been gone for many years. Could that be what you're talking about? Lot of people back in the day used to hook them up to the a/c clutch, to speed the idle up when a/c was on.

[DANTES JIMMY]

This could be way off base but when i wired in my electric fan for the engine i wired it directly to the ignition in the fuse box so that when the truck was running it was on but when i did that when i shut the engine off the truck would keep running and dieseling down to a halt well after quite a bit of beer and head scratching and voltmeter readings as the fan was winding down it was creating a voltage through the windings and back feeding through the fuse box that was keeping the hei supplied with voltage hence keeping the motor sorta running
i used some diodes to correct the problem but then went to a relay and it is all good
so with that said could this relay be there to keep voltage from back feeding through the fuse box to the old coil
as the fan winds down on shut off??
Just a thought

[GuyO]

Very old thread I know, however if anyone else is looking for the location the anti-dieseling relay it is under the dash to the left of the ashtray near the ignition switch.

[fine 67]

i'm pretty sure that the solenid that is on the carb w /ac is to kick up the idle when the air is on .to keep the motor from stalling at idle when the clutch cycles

[old man jimmy]

Originally Posted by fine 67

i'm pretty sure that the solenid that is on the carb w /ac is to kick up the idle when the air is on .to keep the motor from stalling at idle when the clutch cycles

that's how a lot of guys wired them to their a/c clutch....but originaly the plunger kicked out when you turned the ingnition on and retracted when you turned the ignition off. they were an anti=deiseling device..they used them on all gm cars with q-jets.. at least in 72 air or no air.. still have the one on my 72 centurion with 455. some were threaded into the bracket, and you had to unplug them and turn the selenoid to adjust the idle..others had a hex head and you could adjust just the plunger with a wrench..

[yote1234]

for those looking for a factory gm # on these. its #6273301
and some on epay.