2001 S-10 A/C electrical problem?

[txab]

You can have pressure switches mounted on or very near the compressor

[RonnieT]

Ok, had time to mess with the A/C again, yes I had a bad gauge on the 134 Refrigerant   hoses I borrowed.

     The Low Press, gauge worked as suppose to and you use it to allow Freon to flow from can to system or when off it show  line pressure from system.

 I used the 134 hose and put my own gauge on that hose and it registered the same as the low pressure side at 85 psi on the system when off. and the temperature was 95 degrees outside.

     I traced down the wiring diagram starting from the  Climate control head on the dash, the light, blue wire is what sends the signal to the PCM that is mounted on the right fender on the overflow tank.

    The 3 wire pressure switch shows to have 5 volts on one wire and the other is a ground and one is a signal/reference wire that appears to be a type of ground also. No way to really check that with a meter and a test light.

    I undid the factory taped wires  that run across the valve cover to the compressor to find the diode and check to see if it was broken or not allowing 12 volts to the comp.

   It was good.

 Started back on the  relay and the wire that comes from the  PCM to signal the relay .

   It was supposed to be a light green/white stripe wire from a location on the PCM to the relay to click the relay on. I never got a signal from the PCM to click on the  relay.

 I pulled the  relay box off to check underneath for that wire  to see it was broken, it was not and it was Green with white strip.

 I could not find it on the PCM as there were several green with white striped wires there. Didn't know which one it could have been since it would not send a signal.

    I feel like either the  3 wire pressure switch is not telling the  PMC to send the signal or another  sensor is not telling the PCM to make that connection?????

   I did jump past  the #30 and the #85 and caused the compressor to come on and I put in one can of 134   to have some cold air for a bit and while idling I had 45 pounds on the Low side could not say on the high side as I had already swapped back to the bad gauge by then.

    But by jumping the 2 terminals I could make it work.

 Ron

 

 

[Jsdirt]

Sweet! Now we're getting somewhere! 

 

That 3rd signal return wire - that should be showing a voltage somewhere between , say .9v - 4.99vdc - you CAN test this with a multimeter, or an old school analog gauge! If it's flatlined at zero, or close to it (say, .020v),  you've just discovered your problem - that pressure switch.

 

If you can get access to a bi-directional, high-end scan tool, you might be able to pull up these parameters on it to save yourself alot of testing. I should've mentioned that earlier, but, they are super expensive, and not everyone is willing to buy one, or lend them out.

[RonnieT]

Thanks Jsdirt,  I am leaning toward the 3 wire switch as bad.  My reasoning is simple,  something is wrong, nothing has been tampered with or abused, ( I did more abusing the past few days by unwrapping  electrical tape  to get access to wires and pulling out the PCM so I could flip it around to look  for the right wires, and the Relay box  to access it, so the switch is a $20 item, I will work my way up the chain I hope.

   I did find something interesting while  looking for a broken wire.

   I had to pull off the air resonator that lays on top the valve cover and connects to the "throttle body " air  inlet  via  short rubber boot.

 It had a piece broken off and missing on the underneath side  that goes into the rubber boot and was sucking unfiltered air thru that missing piece.

   I live in a rural area where there are no salvage yards within a couple hundred miles  and would have to hunt those down.

     But GM has discontinued the part and I don't know where to get one at,  used it good as long as it  in good condition.  Any clues where to search? is a 2001  2.2  S10  the black plastic box is  about 12"x 6" x6"

    with a 3 " inlet and 3" outlet.

 Ron

[Doug_Scott]

IIt may seem like overkill but.... 

 

https://www.carid.com/2001-chevy-s-10-pickup-performance-air-intakes/?filter=1&sub-model[Liter][]=2.2L

[Jsdirt]

Before you do anything, check about 6" back from the compressor on the clutch coil wiring - they were famous for rubbing through the wires on the heater pipe, and shorting.

 

Also got some better info for  you. This is a variable displacement compressor - no cycling switch is used on this system. The 3 wire sensor feeds exact system pressure to the ECM. Voltage on the signal wire at rest should be around 1v - if it is, your sensor is fine.

 

I don't recall if you tested for power at the clutch coil - if it's present with the A/C on, your clutch coil is bad.

[RonnieT]

1. I think I will hold out for an original Air resonator I don't think I want to complicate things with a cold Air Kit thank you Doug for that,
2.  Jsdirt, Yes I did take the tape off the comp wires looking for the diode  to be bad and it is fine,  That is when I found the bad air resonator , 
3.  Clutch works   as in my post I can short the wire on the relay that gets the signal form the PCM and the clutch works fine them so I am betting on the  3 wire pressure switch  till  I find  if that will or wont fix it.
4.    Ron

[Jsdirt]

Ahh, sorry, missed that part! Got too many emails and forum posts going on at once, lol. 

 

I would still check the voltage on that signal wire - if it's within a reasonable level (not 0v, or 1v, or 4.99v .. but somewhere in between), then the sensor is good. I would hope to see 0 or 4.99v,  so you can definitively say it's bad. Sucks throwing parts at something, only to find you've wasted your money.

[Dnt]

Is it possible to get a good set of gauges hooked up on the truck and short your #30 or whatever so the compressor clutch pulls in and double check the low and high pressure? I would start with the basics, refrigerant has some unusual characteristics and it can fool you sometimes, you might still just be low of R134A or you may have a bad sensor hard to say right now .....

Proper check procedure for pressure testing:  Hook up gauges (please don't forget to purge the lines)  / AC set to MAX / Blower set to HIGH / truck door open or windows down engine at 1500 rpm.  I would get a proper set of gauges and check your pressures before going any further just to make sure you are moving in the right direction. 

[Jsdirt]

^^^ Yep, this is a good plan.

[Dnt]

Sorry I did not mean to butt in on your ongoing conversation. Residential HVAC is my hobby (rental property owner LOL) and I have also done a little bit of Auto AC in the past. I remember when I first started out how intimidating it was and some mistakes that I made that cost me a bunch of money to remedy. You never forget the loud pop of an evaporator splitting because your nitrogen flow gauge was bad and you overpressurized a system when leak checking. Big bummer to pull out the entire dash to replace. Killed an entire weekend.....      

[Jsdirt]

OUCH, yeah that's never fun! Even after all these years of working on vehicles, yanking a dash is one of my most dreaded jobs. I'd rather pull an engine on a econobox! 

 

I don't consider you "butting in" - you offered some valuable input. If I wasn't doing 5 things at once all the time, I'd have thought to offer the same info, lol.  

[RonnieT]

Update,

 I ordered the 3 wire pressure switch ( rural area) and it finally came in last week, installed it ( had a Schrader valve under the connection)

 plugged it in , fired it up, all is cool again!

 I just couldn't get the reference wire to  give me a signal so it was the cheapest part to  get so I started there.

    OK new question, I have an older Lumina that my granddaughter complains the A/C doesn't work,  Yep , the 134A went out of it overnight.

    I have a new reseal kit for the car and the  Accumulator an expansion valve and the 134A ready to go , So I bought a new set of manifold gauges  since I really need them,  they came without the can tap for the 12OZ cans.

   I like the top screw on type  valve so I  ordered a good one, well the threads are toooo big to screw onto the can. the hose tap on the valve fits the yellow hose just right but the can  thread on the valve is too large , I don't know what it fits.

   Can you tell me what the thread size is for the 12oz cans of 134A before I buy another  part I don't need?

The manifold  has the 134 quick couplers with valves   that  unscrew from the red and blue hoses  and the hoses will then screw to the R12 vechiles.

 The yellow hose it says in the instructions will attach to a 10Lb  tank as is  and is  sold without  can valve tap.

 I need the right size for the automotive 12 oz cans. I want to put some dye in it and use my black light to find the leak then put on the new parts and pull a vacuum and recharge.

 Ron

[Doug_Scott]

Don't know the size, but, auto parts stores around here have kits that come with the tap and a hose that cone t's to the manifold gauge set, or you can get a package with a couple of cans with a tap alone. 

Try your local auto parts store.  Take a can with you to make sure you get the right tap. 

[Jsdirt]

Can threads are a standard size as far as I know. I've never seen them change going all the way back to R12 cans. I do remember buying an alternative refrigerant called Freeze-12, back 20 years ago when I was living in Phoenix - was a quick, easy way to get my system cool again. That had oddball fittings and can threads that didn't fit R12 or R134a cans.

 

On the rare occasion that I use cans, I use a piercing tap. I grab it as low as I can (to charge as a liquid), and tilt the can toward the pierce. They're quick and easy ... but if you only use part of one can, it's tough to save them for any length of time.

 

Things were soooo simple before the damned government decided to regulate refrigerants ... there was ONE refrigerant, ONE fitting size, and ONE oil. That was too simple ... 

 

Just FYI, R134a fittings are 1/2"-16. R12 was 1/4" if I remember right. Don't recall the thread pitch. 13 seems to ring a bell ... 

 

Side tap - that's the correct name for it: https://www.amazon.com/Robinair-10102-Side-R134A-Respective/dp/B0009XT7NY

 

Memory is real bad - thread size on car for R12 was 7/16" low and high originally, then they changed to a 3/8" high side. Neither here nor there - doesn't apply!