[Ruh-Roh]

I had the battery tray out, which required me to disconnect the e-brake at the pedal and pull it through the fire wall. I disconnected the two wiring harnesses on the engine side in that area. There are a bunch of wires around the e-brake pedal. I'm sure I put pressure on some of those wires when disconnecting the cable.

I have checked the (one) 25 amp AC fuse in the fuse block and it is good. I disconnected the two harness connectors, filed the prongs and added dielectric grease. Still no AC. I giggled various wires with the engine running and the AC on and the compressor never kicked on.

Does anyone know of a likely problem or other quick things to check?

(FYI, I also messed around with the fuse block in the engine bay trying to find a water leak.)

(93 LT RWD with rear air) AC worked great before this.

Thanks!

 

[Ruh-Roh]

Today I noticed that the 4 wires (orange, blue, brown, and yellow) going back to the rear air were hot to the touch when the AC is on and normal temp when the AC is off.

 

[Ruh-Roh]

Today I took the battery back out and cleaned the ground wires at the fuse block and at the core support and looked for broken wires/insulation. I didn't find anything. I cleaned and greased the connectors again. When I put it all back together the van wouldn't start! So I took the battery back out, ... turns out I left one of the ground wire disconnected! I need more light in my garage. Still no AC, so I guess the problem is inside where access is almost impossible. I'm thinking this is why Astros aren't more popular (But when I look at her I still love her!). I guess I need to get used to taking the drivers seat out and having those studs jab me in the back.

 

[gwd]

Try unplugging the electrical harness again. Look inside to see if it is clean and all pins in place.
Can spray electrical contact cleaner to the plug and socket.
You can add some dielectric clear grease to make the connections from corroding.
It might be the water leak that caused rusting on one of the connection points.

 

[Ruh-Roh]

Are these fusible links? They all attach to a stud on the fuse block, along with the cable from the battery. The Haynes book refers to "underhood fuse - relay center." I don't think a 93 has one unless it is refering to these.

Compressor diagram:

So I'm looking for brown, light & dark green, and white wires under the dash.

When I had the tray out I cleaned around the master cylinder, which is almost directly over the A/C compressor. I hope I didn't mess up the compressor diode or something.

I'm about to pull the doghouse to check the wires under there.

 

[gwd]

The fuses they refer to are in the engine are above the battery.
To see if there is power take a volt meter. set it to read 20vdc or so.
Turn the the dash selector switch to either MAX , Normal or Bi-level.
Then go to the Air-Conditioner Accumulator tank under the hood, left side were the fan blower is located under the black cover area, and un plug the low pressure switch wire.
Take the red lead + from meter and place it into one of the pin connectors on the plug you just removed.
Then take the black lead - from meter and touch ground. One of the wires should show 12 + vots or so.
Light green colour wire according to the electrical diagram you posted above.
If you have power then it is not the fuse nor the dash switch.
Then the problem can be the pressure switch or compressor connection or the unit it's self.
The other possibility is that you do not have enough Freon in the system.
To see if it is a pressure switch, only temporarily place a jumper across the plug connectors and see if the the compressor clutch engages.
If it starts running then most likely the switch stopped working since you say it ran well the other day. Still can be low Freon in the system once it goes below the threshold.
DO NOT LEAVE THE JUMPER IN THE PRESSURE SWITCH CONNECTOR. IF YOU RUN THAT WAY THE AIRCONDITION WILL EXPLODE.

If there is no 12+ power on light green wire at pressure switch then check the fuse under the hood .
Remove fuse cover and under the cover there a diagram showing and naming the fuse.
Take it out and use the Ohm setting on meter to test the fuse for continuity.
The meter will go from o to maximum 1 0r 1000 or something like that on a good fuse.
Reinsert the fuse again. Sometimes there is a bit of corrosion built up on the fuse terminal and by removing it then reinserting it scrapes of the dirt.
Try again the air.
If still not them maybe the dash selector foil contacts have broken.
Would need to open the dash to lock at the knob controls.

 

[Ruh-Roh]

Thanks GWD. I appreciate the detailed guidance!
I don't think my '93 van has an underhood fuse center (I wish it did!). It has those little (~1") black capsule-looking things (4). I think there might be a fuse inside each one (4), but they don't look like they can be opened.

FYI, I had the A/C completely restored about a year ago, including a new compressor. It was working amazingly well, like a brand new car!

 

[gwd]

I think you are using the wrong year electrical diagram.
This should be your fuse box under the dah on the left if I am correct.
Not sure if this the correct illustration. Seams there are a few different pictures.
Take your cell phone a take a picture of open fuse box. There might be a expiation of each on the inside cover.
It is either fuse 10 or 9 in some illustrations for Heater/AC
I do not have my 1993 service manual near me right now. once I get it I will check again next week.

FUSE & CIRCUIT PANEL IDENTIFICATION 1 - 10 Amp Instrument Panel Lights 2 - 30 Amp Circuit Breaker Power Accessories 3 - 30 Amp Horn/Dome Lights, Digital Clock, Cigarette Lighter, Radio Memory, Glove Box Light 4 - 20 Amp Ignition/Gauges, Cruise Control, Headlight Switch, Ashtray Light, Brake Switch, Audio Alarm (1993) 5 - 25 Amp Auxiliary Heater (If Equipped) 6 - 20 Amp Stoplights, Hazard Flasher, Digital Instrument Cluster 7 - 20 Amp Tail & Parking Lights, Headlight Switch 8 - 20 Amp Turn/Back-Up Lights 9 - 20 Amp Heater/A/C 10 - 10 Amp Radio 11 - 10 Amp ECM B 12 - 10 Amp ECM I 13 - 30 Amp Circuit Breaker Power Windows 14 - 25 Amp Windshield Wiper 15 - 10 Amp Daytime Running Lights (Canada Only) 16 - 15 Amp ABS Brake, Speedometer (1993) 17 - 15 Amp Foglights Page 1 of 1 FUSES & CIRCUIT BREAKERS -1993 Chevrolet Astro 4/13/2009 Check #'s 4, 11, 12, ok? No fuse links are just that, fuse links, forget the cigar fuse for now!

 

[Ruh-Roh]

That diagram, from the Haynes book, said "typical for 95 and older v6", so it was probably not exact.

I did the first two checks that you recommended. I have about 13 volts at the plug and the compressor clutch engages when I jumper the plug, so it's the switch or low Freon. Since pressure switches are pretty cheap and I don't have to discharge the system to replace, I'll try that first.

About 10 years ago I had a leak in the Freon line to the rear air. A weld repair was done on it. Hopefully I didn't cause it to leak again when I was working under the van on the e-brake cable.

Probably not needed now, but here is my fuse block:

 

[gwd]

Now you have picture it will be easier to find the correct fuse the next time something shuts off.

 

[Ruh-Roh]

Well I installed a new low pressure switch and the compressor clutch still doesn't engage. I bought the cheap pressure switch off Amazon, so it may be defective.

I looked everywhere that I could see along the Freon lines and didn't find any sign of a leak. I need to get a low pressure gauge. I think I have an old one that attaches to a Freon can. Maybe it will work without the can (?). I'm busy tomorrow. I'll try to check it on Wednesday.

 

[AstroWill]

Apply pressure to your old switch to test it, bet it was working as designed and you are probably just low on refrigerant.

 

[Ruh-Roh]

Apply pressure to your old switch to test it, bet it was working as designed and you are probably just low on refrigerant.

You are correct. The compressor starts with air pressure on the old switches (and the new one). My compressor is only 60 psi and its lower setpoint is 40 psi. The switches activate at 60 but not at 40. Interestingly, once I start the compressor, the clutch will stay engaged to 40 psi as the pressure bleeds off. It does disengage when I remove the air.

Now to find the leak. I talked to the shop that did the A/C work last time and they said they would check it out for me. I was planning to have the rear end rebuilt there anyway. They specialize in drive train work and don't do A/C work anymore due to work load, but they agreed to look at it when they do the differential.

 

[AstroWill]

That is how they are supposed to work, I don't know the exact pressure for that particular switch but usually the low side is ~30psi. Doesn't have to be exact but there does have to be a differential between on and off as it controls the cycling of the system.

I'm sure they will be able to find the leak(s), most of the time you can find them with a good visual, sometimes you will need dye or a sniffer.

Was the system converted to 134a or still using r12?

 

[Ruh-Roh]

That is how they are supposed to work, I don't know the exact pressure for that particular switch but usually the low side is ~30psi. Doesn't have to be exact but there does have to be a differential between on and off as it controls the cycling of the system.

I'm sure they will be able to find the leak(s), most of the time you can find them with a good visual, sometimes you will need dye or a sniffer.

Was the system converted to 134a or still using r12?

It was converted to 134a.

 

[AstroWill]

Might want to use a UV light on it, as it might have dye in it already.

If you have leaked out all of your refrigerant, might want to go ahead and replace all of the o-rings/seals in the system, or have them do it but it would cost more having them do it. 134a has a smaller molecule size than r12 so 134a will leak out easier/faster and doesn't cool as well, but well enough that for most it doesn't matter.

 

[Ruh-Roh]

Might want to use a UV light on it, as it might have dye in it already.

If you have leaked out all of your refrigerant, might want to go ahead and replace all of the o-rings/seals in the system, or have them do it but it would cost more having them do it. 134a has a smaller molecule size than r12 so 134a will leak out easier/faster and doesn't cool as well, but well enough that for most it doesn't matter.

Will, if I add some Freon to the A/C system myself, do you think I would run a risk of adding too much lubricant to the system? I would only add enough to get the dye circulated for detection. I don't want to add much at this time since it might all leak back out.