Cold Aircon

[adrian5800 Advanced Member Find all posts View Profile Close adrian5800]

No worries Steve, glad you got it sorted out. It's a great improvement to the a/c, I get complaints from the strife that it's too bloody cold now..
Soldering the pins on the pot can be a bit fiddly but hey sounds like you have learnt a new skill
For what this mod costs in time and money, it must be one the best value mods we can do to the 120 series.

Cheers

Ades

[gxlman Lurker Find all posts View Profile Close gxlman]

Hi guys,

Excellent mod by the way. I have tried it on my 2006 gxl with mixed results. The thermister on my car appears to be different to the pictures shown in this thread. My thermistor actually push locks into the front of the evaporator. I decided to proceed with the mod anyway to see how it went. Set the pot at 9.5k ohms and then wired into place. With car running at 2000rpm fan speed 2 vent temperature went down to 8 but no lower over 10 minutes. Compressor is not cutting in and out just running constantly. Any ideas? At the moment on a 35-40 degree day here in mackay I am getting between 11 & 13 degrees at the vents cut in/cut out.
Any help would be great.

Also I dont have the climate control model or rear aircon.

I have also heard through people at work that evaporator temps are about 6 degrees less than vent temperatures so if your getting 0 degrees at your vents you would be very close to icing up the evap. Is this right?

Cheers,

Ash

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Hi there Ash, firstly bit confused ?? In first part you say the compressor is on permanently, then you say "" am getting between 11 & 13 degrees at the vents cut in/cut out"" Have you looked under the bonnet at the compressor to determine 100% if its cutting in and out ?? Not having a go at you but this can determine if there is another issue with the system. Also is it genuine toyota air ?? Sounds odd the thermistor going in at the front ?? Not sure how you can tell unless it has nippondenso written on the outside blackbox some where or check the compressor it will have nippondenso sticker on it. The main issue with these systems not cooling enough is there is no heater tap under the bonnet it relies on a plastic flap with a strip of fabric to seal it up (shit idea) I bet if you disconnected you heater hoses under the bonnet and re-routed them the temp would drop big time as the system is now. You may be able to do that due to where you live. Your last comment would probably be pretty write about the temp of 6 in the evap, but in saying that my wifes toyota runs at 2 out the vents genuine air, both my 90's ran around 4 to 5 at the vents with no mods. I just turned myn up a tad last week as it has been running at -1 to 0 then back down again. Even today in approx 34d heat it is now running at 0.8+ upto 1.2+ then back down again. Hasn't frozen up since I did the mod. Worst case if it did I would just turn it up a tad but it didnt at -1 so should be fine now.........Cheers Steve

[gxlman Lurker Find all posts View Profile Close gxlman]

Hi Steve thanks for the reply. Sorry for the confusion. What I meant to say was before I did the mod the compressor would cut out around 11 degrees and kick back in around 13-14 degrees (at the vents) Its definately cutting in and out as it should.

After wiring the pot in set at 9.5k ohms the compressor ran constantly, temp at the vents went down to 8 but the comp never cut out. Sat there for about 10 minutes @ 2000rpm fan speed 2. I was a bit worried about the compressor running continuously for so long, is that bad? I ended up playing with the pot, turning full one way then the other and monitoring but no change.
As for the thermistr, it is definately different as I pulled the blower motor out to inspect (should of taken photos). There is no holder or hole for the bulb like the photos in here show. In your photos there is a little bit of foam above where your thermister goes, my thermister wire is wedged in through that bit of foam then push locks to the evaporator.

Hope this is making sense


Car is going in tomorow morn to get gas level checked and check for leaks.

[gxlman Lurker Find all posts View Profile Close gxlman]

Also great idea about blocking the heater hoses off steve I hadn't thought of that. May help me eliminate the heater side leaking.
I assume its factory aircon, Id have to have a proper look underneath and get back to you.

Edit: Just had a look under the bonnet and the condenser has the Denso symbol on it

[gxlman Lurker Find all posts View Profile Close gxlman]

This is how my thermister is mounted. Definately no bulb.

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Just put both your picture and mine side by side and they certainly look identical even the black striping on the silver pipework, the only difference I can see is the way the thermistor is mounted. Where yours is mounted is extremely close to the heater core flap but still doesnt explain why its not getting colder then 8 and your compressor is still running ?? I think Ive worked out why the compressor is still running is due to the temp not getting down to the set point on the pot so its trying to. It may be low on gas which you can check yourself through the sight glass under the bonnet, if its flowing white foamy liquid then its due for a regas, it could be a stuffed TX valve but I doubt it. Been 35/40d outside is would obviously be working harder to cool down. It doesnt take much for the system not to cool properly. My old 90 was only down 150ml (held around the 750 mark) of refridgerent but was enough for it to struggle to cycle on a hot day. My mate topped it up for me and all was sweet. If you have it booked in anyway Id probably remove the pot for now and put it back to normal and let them do what they need to, which if done properly should be a suck out, replace receiver dryer, refill by measuring the gas and also add a dye to pick up any leaks further down the track. It may have never been touched in 6 years ??....... Cheers Steve

[gxlman Lurker Find all posts View Profile Close gxlman]

According to the shop it has plenty of gas (although at the sight glass its showing white foamy liquid) and no leaks. Everything in the system is working ok they reckon. Theyre diagnosis is a faulty thermistor. Might have to play around with the pot a bit more because the evaporator will have to come out to change the thermistor.

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Why would the evap need to come out to change the thermistor ?? Cant you pull that out the hole like we can ?? Stuff that Id be getting one from a wreckers (thermistor) and drilling a hole roughly where mine is located and whacking it in there, How much foam was in the system. It should only show a tad when the compressor is cutting in and out you will see a few bubbles then it will settle, then when compressor cuts back in it will do the same but SHOULD be clear with no foaming, mine is green as it has a dye in it, certainly no foam when the compressor is running, Wifes is the same..........If it has a constant flow of whitish foaam its low on gas. You may get a slight whisper of it, MAYBE, but if its constant then your aircon bloke has no idea............Cheers Steve

[gxlman Lurker Find all posts View Profile Close gxlman]

My thermistor doesnt have a hole like yours, like my photo shows it is different. I will be grabbing one from the wreckers like you said and making it fit. The reason you would have to remove the evaporator is because the type of thermistor I have is clipped on in the middle of the evaporator with the probe going down inside the fins. Only way I know this is because I removed the blower motor then took the side panel off the evaporator box to get a side view of where the thermistor is mounted.

Theres not much to choose from up here in mackay when it comes to 'specialists' Im down the coast for holidays now so might get a second opinion.

[gxlman Lurker Find all posts View Profile Close gxlman]

My thermistor doesnt have a hole like yours, like my photo shows it is different. I will be grabbing one from the wreckers like you said and making it fit. The reason you would have to remove the evaporator is because the type of thermistor I have is clipped on in the middle of the evaporator with the probe going down inside the fins. Only way I know this is because I removed the blower motor then took the side panel off the evaporator box to get a side view of where the thermistor is mounted.

Theres not much to choose from up here in mackay when it comes to 'specialists' Im down the coast for holidays now so might get a second opinion.

[Bear63 Senior Member Find all posts View Profile Close Bear63]

According to the shop it has plenty of gas (although at the sight glass its showing white foamy liquid) and no leaks. Everything in the system is working ok they reckon. Theyre diagnosis is a faulty thermistor. Might have to play around with the pot a bit more because the evaporator will have to come out to change the thermistor.

Its a good idea to make sure that the heater mixing flap is totally closed, good idea to phyically check this, it only needs to be open a smidge to bring the temp up by 3 or 4 degrees
With R134A ( i assume that's what you are running)the only way to be sure the gas charge is correct is by weight , which means the gas needs to be reclaimed and weighed , the sightglass method isnt accurate enough as a correctly charged system will still show bubbles
when you do your performance test the fan speed needs to be on minimum and on recirc , every vehicle we service that come through the workshop gets an a/c performance test as part of the service and Prados usually run around the 7-8 degrees (vent temp) with a factory system , so Steve M is getting an excellent result

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Hi there Ash, ok thanks for the explanation on how its mounted, sure does make it a lot harder as you have described. Bear is spot on with his comment in regards to the heater flap. This in my mind is 100% an issue as to why they dont cool enough, maybe a cost saving feature by not installing a heater tap. I have tried this on first start up first thing when the engine is cold on my way to work the air coming out the vents is the same temp as what is been displayed on the dash readout say 15d (not engine temp). By the time Im halfway to the main road the vehicles running temp (temp guage) has moved nearly to its operating temp which a tad under half but I have also noticed a rise in the outlet temp on the vents by quit a big difference, say 20/22d while the readout on the dash is still reading 15 so there is definately 100% hot air coming from the heater core flap. This hasnt changed from day one of the vehicle been new. And I have checked the flap and you can hear it close, just a shit design and the hilux's were the same. The other option would be to install an inline heater tap under the bonnet only thing is you would need to operate it manually?? No one seems to complain with the VX's and Grande's with dual climate air so must be a different set up as these are installed in Japan when the vehicle is made where as any GXL, GX etc are put in when you ordered the vehicle new and fitted by the dealer. I think now its standard on all new 150 prados, if not it bloody should be standard in all vehicles in Australia.........Cheers Steve

[gxlman Lurker Find all posts View Profile Close gxlman]

Apologies for the double post. What a great site this is with blokes happy to help solve a problem. May have to become a financial member this site has helped me so much.

Anyways. After getting the car back from the shop they have added die and there is no more bubbles when the compressor is on. I did some tests of my own yesterday before leaving for the gold coast from Mackay. Sitting at idle, 32 degrees on indash sensor, fan speed 2 recirc the temp at the vent is cycling between 11 & 13 degrees, I then wet the condensor with the hose which should bring the temp right down if I am not mistaken but the temperature does not budge from the 11-13 degrees from the vents. Also doing the drive at night with indash indicator showing 21 degrees the vent temps still rock solid at 11-13 degrees. Now correct me if I'm wrong but that makes me think the heater flap is ok and it's the thermistor or thermistor position that is the culprit?

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Ash, mine use to run at 11 when I first bought it, Then I moved the thermistor down and out a tad and got it down to I think for memory 6 out the vents. Then I did Adrian's mod with the pot and got it down to current temp as in previous post. I reckon its the position of it. If you can get hold of another one (thermistor) and connect it up but just hold it, or lay it on the floor and I reckon for sure it will go down and obviously keep going down as it wont be detecting anything. To be honest the thermistor like mine is possibly not that dear for a new one. If I get a chance tomorrow I will ring toyota out of curiosity and see how much they are. At the other end of your thermistor can you disconnect it like mine ?? At least if you can get hold of a thermistor and give this a try before you go drilling holes to mount it or anything it will give you an indication if by moving the thermistor away from the evaporator you will know wether its going to get below 11/13 which I bet it will.........Cheers Steve