SOLVED. PART 2...A/C light blinking mystery (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

So the FSM was followed by the indy shop? Did they bother to take and note pressure readings after the system was filled?

I agree we need some current pressure gauge readings. If the system isn't leaking refrigerant then it *should* boil down (see what i did there?) to a pressure or pressure sensor issue, all other hardware working normally is assumed.

On a side note, is this a fix and flip rig?
 
Last edited:
Sounds similar to an issue I am dealing with. I had some luck by driving at highway speed, turning the auto function on with temp setting to hot, then rolling the temp setting to cold. Would work pretty often this way and would likely go back to flashing if I was stopped such as at a stop light.
 
So the FSM was followed by the indy shop? Did they bother to take and note pressure readings after the system was filled?

I agree we need some current pressure gauge readings. If the system isn't leaking refrigerant then it *should* boil down (see what i did there?) to a pressure or pressure sensor issue, all other hardware working normally is assumed.

On a side note, is this a fix and flip rig?
Mechanic did use proper guages and said pressure readings looked good but I don't remember what they were. The goal was to just check for leaks. At the start of this fun LX event, I put in 36 ounces of freon based on a small gauge I have while jumping compressor. The A/C light would stay on as I was charging but then would go off not long later. Then immediately trying to turn compressor on normally, with freon in, A/C would blink and compressor on for only three seconds.

So thinking that the freon may be leaking as fast as I put it in, I put in some dye and the next day found nothing. I then took it to my realiable mechanic. Again, with leak detecting in mind, he evacuated 38.88 ounces and did not see any leaks anywhere with his black light. He then recharged and continued to get same ol three second compressor. Then checked and found code 47 (rear amplifier) and we decided I would try my good amplifiers from other LXs. I checked front and rear amplifiers and rear servomotor. All good. Then after reconnecting amplifiers there was no code (00). So hear we are.

Neg on the fix and flip. I have to say, I have owned several LXs and have seen several more in my time. This LX is quite a dandy of a specimen other than this A/C issue. Above average to say the least and I got it for a super good price. I am sure I could triple my money on it yesterday. Based on the next time for oil change date and mileage, it has been sitting in garage for a couple years being driven very little.
 
By just disconnecting battery?

Pull the 'CIG' fuse for 10 or more seconds then reinstall.

Did you ever have a DTC 22 code? I don't think you did.
 
No 22. I remember the mechanic pulled the cig fuse to reset. After that is when I got code 47. But now nothing but 21 in the shade.
 
No 22. I remember the mechanic pulled the cig fuse to reset. After that is when I got code 47. But now nothing but 21 in the shade.

Yeah, 21 (solar sensor) would be expected....but like virtually every other DTC for the AC (except for one) also includes the AC amplifier and harness to and from. But you've swapped both front and rear amplifiers with known to be good units with no change.

DTC 22 would indicate a Lock Out Sensor issue. So we would want any currently stored codes deleted, run the system (either until it stops or jump it for a minute, either way). See if any new codes appear.

Since the system pressures have been confirmed by the indy.....then it is starting to point toward the pressure switch OR the wiring somewhere along the way.
 
those guys doing the nav delete in the pre 2003 units have talked about the dials or buttons failing in the used panels they're installing.
did you try swapping in a panel from one of your other cars? That would definitely be on my short list of things to check if I had multiple LX and LC sitting around, along with the clutch relay, even if it looked ok.
txsundevil would be the guy to talk to about the pre 2003 wiring in the center assembly.
I only have knowledge of one instance of the clutch relay failing, and that was questionable.
Before looking at the wring id swap parts in from another car since you have some. Probably a replaceable clutch relay which the later 100s don't have.
The AC SIG wire check and the pressure sensor check. I feel like I should know where the pressure sensor is, but I don't.
 
I popped out entire hvac console from my other working 2000 LX and popped into faulty A/C LX. The good A/C button started blinking in same manner. I also tried amplifiers from my '99 LC. Although the amplifier has different part number the hvac connectors are the same but .....NO GO. I tried a known good relay in faulty A/C, no change. I tried relay with faulty A/C in my other LC and A/C worked fine. So relay is good.

Pressure switch is attached to the freon window behind DS bumper. I may need to switch it out to see but getting a wrench on it without twisting the A/C lines is tricky.
 
those guys doing the nav delete in the pre 2003 units have talked about the dials or buttons failing in the used panels they're installing.
did you try swapping in a panel from one of your other cars? That would definitely be on my short list of things to check if I had multiple LX and LC sitting around, along with the clutch relay, even if it looked ok.
txsundevil would be the guy to talk to about the pre 2003 wiring in the center assembly.
I only have knowledge of one instance of the clutch relay failing, and that was questionable.
Before looking at the wring id swap parts in from another car since you have some. Probably a replaceable clutch relay which the later 100s don't have.
The AC SIG wire check and the pressure sensor check. I feel like I should know where the pressure sensor is, but I don't.

So far...the OP has swapped out several relays (and checked the old ones in other vehicles), so that has been covered. Same thing for front and rear AC amplifiers. The system has been evacuated, recharged, checked for leaks and proper system pressure.


The Trinary Switch (pressure switch) is located in the high side line just below the sight glass. Might be a good idea for the OP to disconnect the connector there and clean it well. Inspect the connector for corrosion, proper fit and note if any wiring is frayed or broken.

^^^^

Edit: B/E posted a moment before me. 👍
 
Pressure switch is attached to the freon window behind DS bumper. I may need to switch it out to see but getting a wrench on it without twisting the A/C lines is tricky.
^^^^^

Very tricky indeed and more than one person has run into that problem.

The Trinary Switch can be quite stubborn to remove. The threads usually have galvanic corrosion and they don't 'usually' unscrew easily.

Also, you will need to evacuate the system of refrigerant before replacing a pressure switch. I'd be more inclined to carefully inspect ALL wiring that you can see in that circuit.

Disconnect and inspect all connections and look for wires that might have been 'chewed on' by rodents when the vehicle sat.
 
it wouldn't be too hard to check for continuity on the pressure switch at nominal pressure, correct?
does it make sense that if there is no continuity in whatever pressure ranges, between 30 low and 400+ hi then the switch would be bad, right?
It's loosing signal somewhere. Maybe that's obvious. idk
was also going too say frayed wires down by the drive belt?
 
Last edited:
it wouldn't be too hard to check for continuity on the pressure switch at nominal pressure, correct?
does it make sense that if there is no continuity in whatever pressure ranges, between 30 low and 400+ hi then the switch would be bad, right?
It's loosing signal somewhere. Maybe that's obvious. idk

Yes, he could ohm it out. Check between terminals 1 & 4. Pull the connector off the switch, ohms should read 990-1210 at 70°F

He could also jump the harness there to see if the clutch would engage and stay engaged which would eliminate any faults in the wiring from that location downstream. I would also jump the condenser fan while there to confirm operation.

It would even be possible to bypass the Lock Out Sensor on the compressor itself...but best to test one thing at a time. Depending upon each persons diagnostic skills, equipment and willingness to dig into it, these things can be anything from easy to nearly impossible to correct.
 
Last edited:
I just disconnected pressure switch. Didn't see any obvious issues of corrosion on terminals or wires, etc. Wires wrapped up in black as they should be. I then checked codes to see how it would detect unplugged pressure switch. It gave me 23 which is pressure switch circuit. Then no code when reconnecting pressure switch. So I wonder if the switch has been bad it would've already given me 23. ???

Testing terminal 1 and 4 are on the outside I suppose. Which I believe the mechanic did but I should be able to as well. I will try to jump terminals now.
 
I cannot get any consistent ohm readings on 1 and 4. Just bouncing everywhere. Other two don't show anything as they should. I did jump harness to engage compressor but for the same three seconds. Could not get fan to jump but I know it was working before.
 
Last edited:
I just disconnected pressure switch. Didn't see any obvious issues of corrosion on terminals or wires, etc. Wires wrapped up in black as they should be. I then checked codes to see how it would detect unplugged pressure switch. It gave me 23 which is pressure switch circuit. Then no code when reconnecting pressure switch. So I wonder if the switch has been bad it would've already given me 23. ???

Testing terminal 1 and 4 are on the outside I suppose. Which I believe the mechanic did but I should be able to as well. I will try to jump terminals now.

Yes, it 'should' have given a code 23....if the pressure switch was faulty or out of spec. But you should still have gotten a code 00 if nothing else was detected.

Trinary switch connector label.jpg
 
Based on your picture of switch, I jumped outsides 3 and 4 to get compressor to engage. Was that magic ?
 
Based on your picture of switch, I jumped outsides 3 and 4 to get compressor to engage. Was that magic ?

Jump 1 & 2 and see what you get. 3 & 4 should be part of the fan circuit....I believe. I don't have my EWD in front of me.
 
I jumped 1 and 2 and got nothing.
 
I just did more jumping. I first pressed A/C button and fan on, A/C light stays on because switch is unplugged. Then based on the numbers in switch picture above....I jumped 1 and 2 and compressor comes on for three seconds and A/C light blinks.

Like before, I then turn A/C control button off then back with light staying on. I jump 1 and 4 and compressor comes on then off every three seconds as long as I keep jumper on it.... but A/C light does stays on not blinking.

Still can’t seem to jump fan on but I saw it on before. I hope I haven’t fried anything jumping wrong terminals.
 

Users who are viewing this thread

Back
Top Bottom