RE: RE: A/C clutch not engaging if really hot

From: Bernd D. Ratsch (bernd@dodgetrucks.org)
Date: Thu Jul 10 2008 - 07:15:43 EDT


The clutch should move evenly. With the mechanic not being concerned or
checking the pressures...time to find another mechanic. A/C pressures are
the first and last test to make sure everything is working properly.

- Bernd

-----Original Message-----
From: Dale Schultz [mailto:d.schultz@sympatico.ca]
Sent: Wednesday, July 09, 2008 8:24 PM
To: dakota-truck-moderator@bent.twistedbits.net
Subject: Re: DML: RE: A/C clutch not engaging if really hot

Hi:
Pressures... I don't know them exactly and the mechanic didn't seem to be
concerned about them after he did the recovery, vacuum and recharge.

Fan Clutch... There is resistance and I can hear a change in the sound of
the
fan as things warm up. I'll have to actually measure the temperature and
strobe
the fan to see if there is clutching action and the temperature it occurs
at.
When we were checking the system at the shop the fan did seem to be engaged
as
we were getting a bit of a burn from all the hot air it was moving.

I tested the clutch coil and manually activated it by providing my own
ground
and 12VDC at the clutch connector. Here's what I got:
Clutch Coil measured 3.7 ohms
With the battery measuring 12.5 VDC the clutch coil would draw 3.5 amps when

activated.

One thing I did notice when doing this test is the way the clutch engages.
The
plate at the front has what seems to be three pins with rubber bushing
around
them. When I apply 12 VDC to engage the clutch it appears as if the plate
only
moves freely on one of the three pins, and only a little on one other pin
and
barely moves at all on the third pin. When engaged the plate has a bit of a

wobble to it when it spins as it doesn't seem to pull in evenly over the
three
pins, is this normal or is it a sign of something binding, which I assume
would
wear out the clutch pretty quickly?

Dale

Bernd D. Ratsch wrote:
> What are the pressures at? What condition is the fan clutch in? What
> happens when you jump the A/C Clutch relay in the PDC?
>
> - Bernd



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