Where is the evaporator temperature sensor?

I'm getting a 13 code on my AC for the evaporator temperature sensor, according to this service manual I have, but then it's not included in any of the component location pics. The best I can deduce is that it's what a pic calls the "thermistor." There's a pic of a test of the "evap temp sensor" being tested by immersion in cold water and it looks like the part with the thermistor name in the pic.

But, that doesn't help. Unlike most of the other components in the pic that have lines showing where they attach to the car or other parts, that pic doesn't connect the thermistor to anything. It's just sitting by itself off to one side.

Better question: is there any other reason for a code 13, before I go to the trouble of water-testing this? The manual says to replace the AC amplifier for a 13 if the sensor is good, or the harness in between. This car operates fine otherwise (not the car with electrical probems).

With the engine running, the compressor clutch doesn't lock when I turn on the AC, and there's not 12v at the compressor connector with key ON, but I can provide 12v to the connector and the clutch clicks/moves as it should. I've swapped all the AC relays with those of a known-good car and both cars didn't change, so I'm assuming the relays are all good.

Figured I just need refrigerant, and the pressure switch was cutting the compressor out. but I'm not confident that my manifold gauges seal properly. Would the compressor not kicking in cause the evap sensor to set the 13 code? IDK where that sensor is, but if I have to remove the evaporator, I bet it's a PITA.

 

Thanks, guys. That doesn't sound good. Getting to the evaporator, from what I can tell, is a major project - refrigerant, coolant, AC unit, blower unit, special hoses in tight places. The manual says there are three possible causes - the sensor, the harness and the AC amp - and checking voltages on the sensor connector tells you which. So, does anyone know it I can access that connector without removing/draining/discharging/etc.? 2 out of 3 solutions don't require replacing that sensor.

Still, does that seem odd, that sensor going bad? Like I asked above - could this code be setting bc it assumes there's refrigerant, or that the compressor isn't turning, etc.? In other words, can the events that trigger the sensor code be the result of other events that, if repaired, will make this code go away? It seems possible if for no other reason there's nothing, possibly, in the evaporator to sense. Maybe be turning the AC on after it sat in the auction for some time and lost it's refrig, is what triggered the evap sensor code.

Yeah, I'm trying to rationalize some way to not pull the AC and blower unit. But, if that's what has to be done, at least I may not have an refrig to collect, and I might be opening those fittings anyway looking for the leak.

 

Thanks, Tom. OK, I confirmed that what the service manual calls the evaporator temperature sensor is what the wiring manual calls the AC thermistor. Still can't tell where the connector is. Here's pics. One shows the dash locations of many components - the thermistor is A12. It's line points to what looks like a spot right next to the AC amplifier by the AC controls in the dash.

However, there's no matching connector on the amp. All the pics show the thermistor with it's own 2-wire (loop) connector, but the wiring diagram and a pic of the amp terminal pin outs (not incl) don't show a spot for a separate 2-wire connector going into the amp, even though the illustration shows the connector right by the amp.

Good news, this is the car that I replaced the dash bezel in last month - broke it trying, but am still using it. So, it comes off easy. My hope is that I've simply not plugged in that connector putting it back together.
therm-insp hosted at ImgBB — ImgBB
therm-dia hosted at ImgBB — ImgBB
thermistor-loc hosted at ImgBB — ImgBB
ac-unit hosted at ImgBB — ImgBB

 

Thanks for helpiing. I'm probably not communicating well. My confusion is that the pics of the thermistor show it with the two-wire connector. Here's the pic of the test page showing the connector and two test leads:

thermtest hosted at ImgBB — ImgBB

All the rest of what you describe is exactly why I'm confused. The wiring diagrams shows the sensor circuit beginning and ending in the amp terminal connector and doesn't show any two-pin connectors, splices, JBs or any such interruption to the circuit where the two-pin connector can join.

If there's no two-pin, if the circuit is direct-wired to the amp, that'd be fine, but there'd be some different way, if any at all, to test the sensor.

Do you have an opinion as to whether that DTC could be a secondary effect of some other issue - maybe something not producing whatever the sensor is supposed to sense?

I do see those Blower Unit instructions, with the brace feature in the manual. It doesn't look too hard. Just don't want to go there if I don't have to.

I still don't have refrig pressure readings that I trust. I believe there's none. An evap sensor wouldn't cause a loss of refrig, so if it's empty I definitely have another issue. I'm going to get the pressure checked today. I'm thinking that I can pump some refrig in to see if it kicks the compressor on, find the leak, and fill it up, whether the evap sensor is bad or not and won't lose the frig. But, if I had to remove the AC unit to get to the evap, then I'd have to evacuate the system again.

Do you think a bad evap sensor circuit would stop the amp from powering the compressor to let me go that route?

 

Thank you, sir. Everything on hold a few days now for a funeral.

 

OK, we may have answered that question - no refrig can lead to a code 13.

The tech's gauges said my refrig was low. He put half a can in and the AC kicked right on. But, we could also hear it leaking out the condenser. This car had the slight front end wreck and it didn't look like the condenser/radiator got damaged to me, but apparently so. My parts cars have good condensers, so I'll swap one over. probably get a new dryer, etc. I assume I've lost all my oil too? I think these cars take different compressor oil than my other old cars. Pull a vacuum, and it should charge right up. We'll see if the code comes back.

My father passed today so I won't be able to finish this until later next week. I'll get them swapped over the weekend, but not charged up before I leave. I'll update.

 

Thank you, sir. He was 92 and had a good life. He died in peace.

 

Thx, Tom. Yep, my generation is falling like dominoes these days. And definitely more light from one end of my tunnel than the other. I'm just fighting through that hard time when you learn to accept it.

 

Well, that didn't work out. I have so much going right now and don't have the energy to mess with this car. Plus, I wanted to help the son of a mobile tech I knew who passed away last year. The son took over his business.

I don't trust my HF manifold gauges, and had got him to help me find the condenser leak in my AC. So, I pulled a known-good radiator/condenser assembly off my parts care, but I paid him to put it on this car and charge it up. I picked it up today and the AC seems to work fine, but I didn't get to test it much because there was a CEL on now. A p0115. I just live a mile from there, but before I could get it home, my temp light lit up. I slowed down to make the ICE stop and coasted home on battery. Before I got there, the temp light went back out, as I expected it too.

So, that made me think it really was getting hot, and not just the coolant temp sensor issue that 0115 points at. I think the issue is that my tech didn't fill it all the way up with coolant. He only had to drain a little out to keep it from coming out the radiator hoses when disconnected, but that would still leave the radiator full. So, I provided him an entire radiator assembly, but it wasn't full of coolant. I think he added back in what he drained out, but didn't add enough to refill the swap radiator.

No problem. We discussed it before I left, and I had a gallon of Toyota coolant at the house. All he had was green stuff.

So, I think that solved that problem, but the inverter reservoir was low too, so I topped it up, but it was leaking out. Turns out it's cracked the back ear off, so bad that the reservoir is leaking. And the hose that carries that coolant attaches to the radiator fan shroud. The tech had to move it out of the way to pull the radiator/condenser assembly. I expect he pushed it too hard, maybe the plastic is brittle, and broke the reservoir.

Tough luck, but no biggie. I have spare reservoirs. But reading the manual, the only removal process it describes is to remove the entire inverter, then taking the reservoir off as part of a disassembly process. I can't find a "removal" process for just the reservoir. It looks like the two mounting bolts can be accessed, but the two bolts that seal the fluid port into the inverter would be hard. There's a plastic-framed collection of hoses? fuel line? something between the reservoir and the ICE heads.

Has anyone replaced just that reservoir? Can I move that plastic assembly out of the way to access the reservoir's bottom bolts without yanking the entire inverter?

 

Dang, so that means taking the wipers/cowl off to get one of those back inverter bolts. Was hoping to get those two bottom bolts coming from the passenger side by removing the hoses. I'll find out taking the one off I guess.