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Please help me play detective on this conversion

2K views 8 replies 4 participants last post by  Audiomaker 
#1 ·
Hi guys, I don't mean to over-post and ask the same questions in multiple threads, but just this once it seems like it might be helpful (mostly to me...lol), so please forgive me but I have to put all the symptoms in one thread.

Ok, I just got this rig... which is a V8 350ci TBI conversion (97).

Currently the oil and temp gauges don't work, the cruise doesn't work, the A/C clutch doesn't engage, and the air flow is stuck in defrost.

The cruise I think wasn't installed, or at least I only find one linkage to the throttle that I can see (the pedal).

Now I realize there is every possibility that all of these items just happen to be individual problems. The conversion appears to be well done... not hacked. There are fresh vacuum lines through most of it, wiring is in harnesses...secured...mostly clean with no "bypasses"..etc.
Point is, it looks like someone tried to take the time and expense of doing it right. It's not just motor hacked in there with a fuel line running through the interior of the van to the tank, and cobbled together electric...etc. I've done conversions on other vehicles, so I can appreciate the work and the thought process behind it.

So there's a couple ways to look at this. First, it seems unlikely that the installer/converter would just "forget" to hook this stuff up, or hook it up wrong and let it go (40k since the conversion).

On the other hand, it seems like a lot of related stuff (two dash gauges : A/C compressor *and* diverter box) going wrong at the same time after what was relatively recent and major attention put to the motor and vehicle.

So my question is... is there one, or two sources that would cause 4 problems (ie...a fuse will take out several things, or a single faulty harness plug)?

Because of the nature of these problems combined with the recent conversion, I'm trying to see if I need to start "upstream" looking for a different point of failure as opposed to possibly trying to fix 4 individual coincidental failures (oil/temp/diverter/ac).

I have already jumped the connector at the condenser (or is it the dryer?)... (top rearward pressure switch on silver cylinder) and the A/C clutch did not respond on max A/C.
I did this thinking possible the refrigerant is low/out because *that* is something that will happen when doing a conversion... maybe they never recharged it...etc., but I couldn't force the issue.
Again this points to an "upstream" problem (ie...no point in the next step being testing for a bad clutch), and I decided to stop there and ask so that I'm not diagnosing all of this in the wrong direction.

So.. fuses... main relays...sub computers...ignition not getting to some "area" that would affect several things at once?

Ideas?
Sean
 
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#2 ·
UPDATE:

While I was waiting, I went ahead and pulled the passenger wheel and yep... the vacuum line had gotten disconnected from the vacuum canister.

So... stuck in defrost problem solved (grateful to the board). A/C clutch didn't magically kick on though.

Maybe this is 4 coincidental problems after all....weird.

By the way, the temp gauge reads zero, but the oil pressure gauge is at max. Is that normal for a bad sensor or being disconnected?

Thanks
Sean
 
#4 ·
Silver A/C related thing with the pressure switch on the back = ACCUMULATOR

Water temp sender is a THERMISTOR. As temp INCREASES, resistance DECREASES. DISCONNECT the wire from the temp sender and it has infinite resistance. The temp gauge should read zero. GROUND the sender wire and the resistance is near zero. The temp gauge should read FULL hot.

Oil (and other) pressure senders are similar. GROUND the wire and the gauge should read FULL. Disconnect the wire and the gauge should read zero.

I think I'm quoting both of those right. Someone please check my work.

There has to be key on power to make either of those circuits happen. So in most electrical gauges, when the power is off, they read zero. In old style mechanical gauges, the needle would stay at the setting till the water cooled (half an hour) or till the oil pressure dropped (seconds).

Lump
 
#5 ·
Lumpy said:
Silver A/C related thing with the pressure switch on the back = ACCUMULATOR

Water temp sender is a THERMISTOR. As temp INCREASES, resistance DECREASES. DISCONNECT the wire from the temp sender and it has infinite resistance. The temp gauge should read zero. GROUND the sender wire and the resistance is near zero. The temp gauge should read FULL hot.

Oil (and other) pressure senders are similar. GROUND the wire and the gauge should read FULL. Disconnect the wire and the gauge should read zero.

I think I'm quoting both of those right. Someone please check my work.

There has to be key on power to make either of those circuits happen. So in most electrical gauges, when the power is off, they read zero. In old style mechanical gauges, the needle would stay at the setting till the water cooled (half an hour) or till the oil pressure dropped (seconds).

Lump
Accumulator = Thanks. Obviously A/C aint my 'thang. Yeah... jumped that sender with zero result.

I also recharged the A/C using A/CPro DIY stuff (done this once before on my 1994 K3500 and worked great). System had zero pressure, but even after forcing the compressor clutch on jumping the "A/C enable relay" while charging the system, I am able to get the truck to cool, but not without jumping that relay (meaning the pressure switch on the accumulator doesn't seem to be the issue).
I even replaced the "A/C enable relay" and checked all the fuses. So now the A/C works... the diverter box works... I just can't get the A/C to turn on and off via the climate control switch. I guess I'll continue this topic in the climate control section, but it does appear that at least the diverter box was it's own unique issue.

My Oil temp reads full (even with the truck off), so that's a clue. Some cars do this, most don't (with temp too).

Anyway, the point of this post was to see if any of this might be related, but I guess I just "lucked out" and got 4 unique problems at once.

You know how it is... you get a "new to you" model truck and spend a week tracing stuff and someone goes "Oh yeah... that's the hidden inline fuse behind the passenger kick panel"...etc.

Now with the diverter box fixed due to the standard vacuum issue, and the A/C system charged and cooling (i.e....having pressure), it's down to a few electrical gremlins that I would not presume are related....and that's a big help.

I left the title vague enough that the search engine should miss it for the most part.

I appreciate the help... now... temp gauge at zero, no big deal. Oil always reads full?.. well that one's a bit odd.

Sean :)
 
#6 ·
Just a side note.On Ebay there are companies that sell factory service manuals and electrical supplements from the factory for those manuals. These manuals where published for dealer techs to use. You can get them fairly cheap and it will give you info unlike anything else. Really good tool to have in hand.
 
#7 ·
Here it is:



This gauge state doesn't change even with the battery disconnected.

Soooo.... If that's not where the oil pressure needle is supposed to live with the ignition off (or disconnected battery) on a 1997 Astro, then I have to assume the gauge is broken or at some point was given full ground (or was struck by lightning) and stuck there.
No point in checking senders prior to fixing that.

It's just so damned high that normally I'd suspect it lives there until getting ignition and sender feedback, but ok.

Just one more time fellas... this is wrong, right? Sorry, I haven't seen many gauges stuck like this.

Thanks
Sean
 
#9 ·
chevymaher said:
Audiomaker said:
Just one more time fellas... this is wrong, right? Sorry, I haven't seen many gauges stuck like this.
I can't make the call what is wrong. But something is definitely wrong.

I going with the lightning strike theory myself that is fried.
Ok... just wanted to get the pic' up to make sure I was explaining the situation correctly. So out comes the dash pod...ugh.

Thanks all :)

Sean
 
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