Climate Control Problem

[JIMSVX]

Today I did some extensive driving in the heat and discovered a new characteristic of my ailing air-conditioning system. Right out of the garage it started out working great as usual. Then within 10 minutes I began smelling the humid odor that signals the compressor was turned off. It cycled on and off for a short times but not enough to keep the cabin anywhere near comfortable. From my aerospace days I recalled that sometimes we would cycle the power to a system and it would come back into operation when it was turned back on. So I shut down the AC for about 15 seconds and turned it back on. The AC came back up and started cooling again. I don't think it was operating at 100%, but it was livable and even cool (the outside temperature was running in the mid 90's.) It continued cooling until I reached my destination about 20 minutes later. On the way home it shut-down again about 8 minutes into the trip and a 15 second shutdown cleared it up again.

When I got home I ran the self-test and it returned codes 13 and 14 (Sun Load Sensor & Evaporator Sensor, both open-circuit.)

Tonight while looking in SVXIpedia under the section "How to Check Climate Control Trouble Codes" (this link) there is a statement that I don't think I understand. It says,
"Anytime codes 13, 33, 34 or 35 are displayed, the condition is one which is currently occurring."
I don't know if I understand for sure what this means. Does it mean that if the Sun Load Sensor fails and then starts working again it won't show a code 13 in the memory? Since we are all reading code 13 I was wondering if this has any significance.
- Jim

[lee]

Originally Posted by JIMSVX

...snip...
I don't know if I understand for sure what this means. Does it mean that if the Sun Load Sensor fails and then starts working again it won't show a code 13 in the memory?
- Jim

Yes. it only throws a code if the problem is currently happening - otherwise the system would be throwing a sunload sensor error every time you drove at night. however the sensor is a solid-state device - it's unlikely to work, then fail, then work... etc.

[lee]

Originally Posted by gsodonis

I have the exact same cooling issues as well! My only saving grace is that the AC runs more consistently the hotter it gets outside. In the spring when the temp was in the upper 70's, my issues were the cycling of the compressor. Now that it's in the 90's (in TN), the AC seems to run fine. I'm betting that I have issues in the fall.

This appears to be a common problem. I wonder what result we'd have if we did a poll? There are probably more SVXers with this problem that haven't replied to this post. I'm prepared to offer a reward to the person that correctly diagnoses this problem. It's probably a sensor (or two). The question is - which one?

Has antone out there solved this?

Since the trinary switch cuts out the compressor with either too much or not enough pressure, and since pressure builds with heat, I'd make a WAG and say you were marginally under-filled. However, this either has to be tested with gauges coupled with ambient temp pressure charts, or do as Beav suggested - drain, vac and refill.

[gsodonis]

Originally Posted by lee

Since the trinary switch cuts out the compressor with either too much or not enough pressure, and since pressure builds with heat, I'd make a WAG and say you were marginally under-filled. However, this either has to be tested with gauges coupled with ambient temp pressure charts, or do as Beav suggested - drain, vac and refill.

Thanks to all for keeping this thread alive. I have a buddy that has all of the gauges and tools. I'll have him check the pressure and report back. Currently, my AC runs perfectly (and has since June), so the pressure (no pun intended) to get it looked into hasn't been high.

I'll report back what I find.

What is the Trinary switch? Is that the switch inline with the condenser under the hood below the right hand headlamp? I'm looking it up on www.subaryparts.com but can't find it. Now, I said that I was going to be doing some tests and wouldnt stop until I found the problem. I got the under dash sensors Friday from a car in the salvage yard. Replaced them and still the same problem. That leads me to believe that my problem is with the sensor that is in the tube that comes from the condenser (High pressure switch?) It seems that the only way to get this sensor is to buy part#73431(I).which is (Pipe-Condenser-Liquid Tank). Anyone have this problem before?

[gsodonis]

Originally Posted by overdalimit

What is the Trinary switch? Is that the switch inline with the condenser under the hood below the right hand headlamp? I'm looking it up on www.subaryparts.com but can't find it. Now, I said that I was going to be doing some tests and wouldnt stop until I found the problem. I got the under dash sensors Friday from a car in the salvage yard. Replaced them and still the same problem. That leads me to believe that my problem is with the sensor that is in the tube that comes from the condenser (High pressure switch?) It seems that the only way to get this sensor is to buy part#73431(I).which is (Pipe-Condenser-Liquid Tank). Anyone have this problem before?

That sound like the high pressure switch. My dealer looked it up and it only comes with the high pressure pipe/hose. It's around $100. I haven't switched over to 134 yet and am holding off until the AC starts acting up again. At that time, I'll replace that line/switch combo and do the conversion.
When I described the way our AC's are behaving, a couple of automotive HVAC guys I know both said it sounded like the high pres switch, so this sounds promising.

[UberRoo]

I've noticed similar behavior. Infrequently after running the AC for an extended period of time on days when the ambient temperature is only moderately warm, the AC will shut down briefly. Cycling the system by turning it off and waiting does work, but only briefly. It's not particularly bothersome because it only happens when I don't really need the AC anyway.

Another situation I just noticed is that the AC shuts down when the engine gets a little too warm. I was pushing my motor really, really hard the other day with the AC blasting. When the temperature gauge began to climb, the AC shut down. (Followed by the transmission locking up the torque converter at all times in both third and fourth gear and holding gears as long as possible.) Anyway, once the engine cooled down, the AC came back on. What I noticed was that there's a gap between the AC turning off and the transmission going into "damn it's hot" mode. I think a thermostat that was about five or ten degrees too hot would prevent the AC from working without freaking out the TCU. The needle on my temperature gauge rests very stable at the nine-o'clock position. At about nine-thirty, the AC quits.

[Earthworm]

Another cause for sporadic A/C is moisture in the system. If you haven't then now would be a good time to convert to R134. A replacement dryer is strongly recommended even if not converting.

Definately the system should be evacuated, vacuumed, checked for leaks and recharged.

[Beav]

Originally Posted by JIMSVX

there is a statement that I don't think I understand. It says,
"Anytime codes 13, 33, 34 or 35 are displayed, the condition is one which is currently occurring."
I don't know if I understand for sure what this means. - Jim

In automotive parlance it means, "You are in the midst of a cluster f**k and this is how this particular device reports the error when it doesn't know exactly what is happening."

Generally speaking two issues create a large number of error codes in any system - defective control units and circuit/power deficiencies/oddities. Now you have to take that statement with a grain of salt and a grin. An intermittent issue can cause a power/circuit issue that wasn't intentionally designed to occur. Difficult to write a tech manual around "What can happen if something weird occurs:..." And then obviously if a control unit begins going south all bets are off on what codes will be spit out.

The point of the informational sentence is, "We don't have a friggin' clue, we didn't design the system to have this problem. Make your best guess by following what the actual problem is and don't chase wild geese trying to fix a code that doesn't represent the actual symptom(s)."

Welcome to my world.

[JIMSVX]

Originally Posted by Beav

In automotive parlance it means, "You are in the midst of a cluster f**k and this is how this particular device reports the error when it doesn't know exactly what is happening."

I thought that's what they were trying to say, without really saying it. After 40 years at Boeing, troubleshooting F-15's and F-18's, I though I had seen every possible way of saying the same thing. It seemed like every problem we ever had with the avionics systems had never before been seen by anyone else.

We had systems that would spit out 10 or 15 trouble codes at the same time. Experienced technicians could look at the group and see the pattern that told them where the single failure was. We tried to develop an Artificial Intelligence system that the "Customer's" Maintainers could use to fix these troublesome jets. It was never able to duplicate the logic that our technicians had in their brains.

I'll go back to making my best guess without throwing a lot of money at it. Thanks for your help.

- Jim

[pearlm30]

I have exact same thing, did some search and really hate to dig up this old thread, but did anybody solve this problem???
Thanks

Originally Posted by overdalimit

I've got a 95 SVX and well I've had an A/C problem for quite awhile. I performed the diagnostics and got a code 13 (Sunload sensor). Here's the problem.

Once I start the car and turn the A/C on AUTO mode sometimes the blower won't come on for quite a while. You can here the blower motor barely spinning and then it will gradually go from low to high as it should. Sometimes it comes on immediately after starting the car, which it should.

Now, After the damn thing has started blowing and the compressor decides to kick it its ok. then all of a sudden the blowers running full blast but the compressor decided to turn off. A few seconds or minutes later the compressor decides to kick in again. Now, this is not due to a low charge but it's something electronic.

What it all equates to is a A/C that works for a little while and then stop working. It's not low in refrigerant at all.

Sometimes I hit the AUTO button and nothing happens...then all of the sudden the blower goes to high and the compressor will kick in...it'll cool for a few minutes then the compressor turns off and the blower is still going full blast like a stupid sensor or something is telling the system that the desired temperature has been reached and it can turn the compressor off.

Look...I need help with the thing..HAS anyone experienced this?

Like I said, The only code that the Self Diagnostics indicates is the Sunload sensor.

[BeneathNorthernSkys]

having the same problem, is our A/C an R-134 unit?

*I've answered my own question, ignore the post lol

[pearlm30]

Just an update
Looks like I fixed the problem. I swaped out the evap unit (with a known good 92 )under the glove compartment, thinking it could be the partially clogged expansion valve.
Vacuum the system and put in 2 can of R134 (24 oz) and it keep blowing cold and didnt cut out like before. Drove it for over 50 miles at about 94F hot and humid weather and not a problem.
Hopefully this thread will help out someone in the future.