A/C blinking light - over-pressurized? Bad ground?

EDIT #2: Solved, I think. Check my third post below for info. I'm leaving this up for anyone else looking for info in the future.

The A/C in my 2003 access cab, 151K miles, just stopped working. This being August in Phoenix, I need to get it fixed asap. It was working, then it stopped and the interior light just blinks.

Background notes:

• I just had my timing belt, water pump, thermostat, drive belt replaced about 200 miles ago. Suspicious timing?
• I have had my windshield replaced several times, and most recently there is a slight leak on the passenger side. This being Arizona, and I have Weathertech floor mats, I put this issue on the back burner. This is relevant for point #2 below.

I've been doing some research and found the following info:

1. Compressor's ground strap: mine seems to be tight.
2. Windshield leaking water into someplace. I found (and somehow lost) a thread about the windshield leaking water into a switch or something, so it definitely could be that. Things should have dried out since the rain Saturday when it stopped working, but something could be damaged. I can't find the thread that mentioned it, though, to find where or what that location is.
3. A/C relay: I've read about testing by swapping with the horn relay, but I can't find relevant info for 1st gens. Nothing on my fuse block diagram, the Haynes manual, or this forum (that I could find) mentions this relay for our older trucks.
4. Low coolant: Somebody mentioned that an extremely low refrigerant level could cause this, and mentioned the viewport in the front of the truck.

I had noticed bubbles flying around in there, a while ago. I admit I don't know what that viewport is for, or what I should do about it.

In any case, I had some refrigerant on hand, so I figured I'd check that too. Connected the gauge to the low pressure port and the pressure needle pegged ALL THE WAY AROUND. WTF.

I haven't touched the A/C system in a couple of years. I certainly haven't added refrigerant recently. Not sure how it could be radically overpressurized.

Questions

1. Could the timing belt job have caused this?
2. Should I release pressure? Given that it has been in equilibrium for years, seems odd that it is suddenly off the chart.
3. If so, how?

 

Update:

I went back to double check a few things. Noticed that yes, the bolt on the ground strap (I assume) is tight, but the assembly between the ground strap and the compressor is very loose and wobbly. (See diagram.)

In other words, it seems like the bolt may be wrong and doesn't properly clamp it all together tightly? Or is it supposed to wiggle for some reason, to reduce strain from vibrations?!

That doesn't seem right, but the bolt is tight, so not sure?

And still not clear on how that affects the overall system pressure? Must the compressor be running to get an accurate pressure reading?

 

Update: decided to just test something and see: I put a metal binder clip on the bolt head to connect it all together tightly, and the A/C seemed to work. No blinking light for quite a while, i.e., different behavior than earlier.

Solution: Seems indeed to be a bad ground after all.

I added one washer to the bolt and assembly, and that seems to be enough to make it fit tightly. The bolt does look old, and it's short, so...maybe cross-threaded or something?

I'm guessing the mechanic didn't put the right bolt in, or cross-threaded it, when reassembling after the timing belt job. Not sure why it took 200 miles to be an issue, but at least that seems to be the cause.

 

Or....he just wants you to be a repeat customer. Fix one thing, break another.

 

Funny, but I don't think so in this case: this guy is so busy I can't get in to see him when I want to. I beg him for appointments for things I can't handle myself, and I'm lucky if I get in in the next 4-6 weeks.

 

Well then it's probably just an honest mistake. I can only cite my history where for example I've gotten my water pump replaced under warranty and as I'm ready to go home, find one of my CV boot straps missing and spitting grease before I even left the dealership. Having worked underneath my truck a few days before, I knew it was foul play.

 

I mean, I guess that's a good thing? Either you're in a really busy area, or his reputation is great thus extremely sought-out.

Glad you seemingly got it fixed. If I wanted to know the story, I'd get a finishing nail or similar rod, and test the depth of the hole with the bolt removed. If it's way deeper than the hole, maybe wrong fastener? If the hole is shallow, and it's a short bolt already, there's a solid possibility a fastener got snapped off in there already. Or this may just be a case of "the shop lost the shim/washer". Maybe another '03 owner could snap a pic of theirs. I'd expect a hex-head bolt vs. philips screw there, but I dunno.

But yeah, that little ground at 3 o'clock, there's no way in hell that was getting good ground with the fastener that loose.

 

Yeah, getting a photo from another '03 owner would be great: when I looked I thought "that phillips head looks out of place". I'd like to know what it is supposed to be.

 

Here's the parts diagrams for the '03 AC 4WD if you wanna go down that rabbit hole. https://parts.toyota.com/Toyota_2003_Tundra-Access-Cab-Limited-47L-AT-4WD.html

I think you want the Heating & Air Conditioning section specifically: https://parts.toyota.com/Toyota_200...-47L-AT-4WD/Heating-and-Air-Conditioning.html

Probably the Compressor section: https://parts.toyota.com/a/Toyota_2...IR-CONDITIONING---COMPRESSOR/841420-8719.html

I think one of these will be correct, you tell me which? Pretty sure it's the 1st one based on the harness, plate ("88688K" is your "very loose" part, I think?), and the ground strap shown in this exploded. 16¢ for p/n 9331915008 (formerly 93319-15008) and it's labeled as "screw with washer" so maybe your problem was just a lack of washer? I did a deep dive and found this pic btw:

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Or possibly 21¢ with p/n 9006804022 (is the new number, 90068-04022 is old) but it appears it uses a washer also. The wire harness doesn't look right to me but these exploded diagrams are hard as hell to tell sometimes.

 

You're the GOAT, @shifty. The ground wire screw on the compressor is indeed 9331915008. There's always one rouge fastener than decides to poof out of existence...

EDIT
So the dealer didn't have 9331915008 on hand, so I went and grabbed a few different sizes of machine screws at the hardware store.

An M4-.7mm x 8mm screw seems to fit just right. Tightened down the bracket and no play in the ground wire whatsoever. Just a heads up for anyone out there that has fat fingers like me!