A/C B1421 and B1428 Solar Sensor problems

genius149 · August 30, 2019

My LS430 facelift is giving me even more headscratching problems. I had it booked in for a regas at Halfrauds today and they kindly filled it but unfortunately it still blows warm air through. The advantage of this is that they said they couldn't charge me so I've saved myself £40. They ran their diagnostic on it and it came up with codes B1421 and B1428, front and rear solar sensors accordingly. It's a start, but where are they so that I can check them and clean or replace as required?

I've read other posts that say the front one is under the driver's side dash - if it is, how easy is that to get to? 😱

I've no idea about the rear either. Also, can I run some sort of self diagnostic test and is it better to do it on a sunny day or a cloudy day?

I may have loathed my A6 but at least the air-con worked!

Herbie · August 30, 2019

1 hour ago, genius149 said:

I've read other posts that say the front one is under the driver's side dash

Sorry, I don't know the answer to your question but it would seem very strange for a "solar sensor" to be under anything - surely it's purpose is to detect sunlight/daylight/temperature so would need to be up near window height somewhere?

It also depends where the car was when they ran the diagnostic. Because it's looking for solar radiation (light) if the car was in a garage bay or somewhere out of daylight, it wouldn't be unusual for these codes to come up. Try clearing the codes and look again in daylight or when shining a torch on the sensor.

genius149 · August 30, 2019

Well that was my logic but this clublexus thread on the rear makes me think differently. I'm confused!

This is a diagram of the front...even if it is somewhere on the top, it's what's underneath that I need to look at and investigate.

messi · August 30, 2019

Solar sensor has nothing to do with air con, solar sensor will throw up a fault during the day but not in the evenings and that's because it controls the auto lights

Herbie · August 30, 2019

I would have absolutely no confidence in Halfords to do something like this anyway.

As we know from another recent thread someone on here took their RX450h hybrid to Halfords for a regas and they caused hundreds of pounds-worth of damage.

The branch he used didn't have a proper aircon machine to carry out the work. All they did was to basically use a 'top-up' can of gas, open the tap until no more would go in and then close the tap. The proper procedure is to hook it up to the machine, recover what gas is in there and check the quantity, pull a vacuum on the system and see if it holds and if it does, refill the system with the correct amount of gas.

What I'm saying is that if they've done the same on your car, maybe it's simply still blowing warm because it's not got the correct quantity of gas in the system. I would take it to a proper aircon specialist to let them diagnose it properly.

messi · August 30, 2019

I agree with the comment above, you shouldn't have taken your car to Halfords unless you really really hate your car, Halfords technicians are useless and will cause damage to your car

Herbie · August 30, 2019

Although the text is mangled these may help with locating what you need - but I'd still take it to a specialist anyway:

genius149 · August 30, 2019

51 minutes ago, messi said:

Solar sensor has nothing to do with air con, solar sensor will throw up a fault during the day but not in the evenings and that's because it controls the auto lights

That makes sense - My auto lights work fine and after seeing where they are, I'm not worried about those codes now.

31 minutes ago, messi said:

I agree with the comment above, you shouldn't have taken your car to halfords unless you really really hate your car, halfords technicians are useless and will cause damage to your car

I admit to avoiding them whenever possible but I would disagree that all their technicians are useless. If they had ruined my car then I'd agree but they haven't so I'll still reserve my judgement.

18 minutes ago, Herbie said:

Although the text is mangled these may help with locating what you need - but I'd still take it to a specialist anyway:

Thanks for this, the first one I shouldn't need but this is a good place to start. Tomorrow's the day for tinkering.

The-Acre · August 30, 2019

A couple of weeks ago I "filled" the AC on my wife's Vauxhall with the can of gas that Halfords use bit to no effect. We then took it to a specialist who charged £80, emptied it, did a vacuum test, filled with the correct amount of gas and PAG oil and all is fine.

TigerFish · August 30, 2019

1 hour ago, messi said:

Solar sensor has nothing to do with air con,

This is not true. The solar sensor does form part of the control circuit for the air conditioning. It is true that it does also control the auto lights.

If they did the diagnostics inside the workshop, it is possible it wasn't getting enough light, which will throw the fault code. Shine an inspection lamp on it and the code will likely clear.

ColinBarber · August 31, 2019

There are typically two sensors, one for AC and one for the auto lights.

royoftherovers · August 31, 2019

13 hours ago, genius149 said:

My LS430 facelift is giving me even more headscratching problems. I had it booked in for a regas at Halfrauds today and they kindly filled it but unfortunately it still blows warm air through. The advantage of this is that they said they couldn't charge me so I've saved myself £40. They ran their diagnostic on it and it came up with codes B1421 and B1428, front and rear solar sensors accordingly. It's a start, but where are they so that I can check them and clean or replace as required?

I've read other posts that say the front one is under the driver's side dash - if it is, how easy is that to get to? 😱

I've no idea about the rear either. Also, can I run some sort of self diagnostic test and is it better to do it on a sunny day or a cloudy day?

I may have loathed my A6 but at least the air-con worked!

How long have you had the car and did you buy it from a Trader ?

Edited August 31, 2019 by royoftherovers
typo

OldTrout · August 31, 2019

Neil,

At year ago at service, my garage flagged B1421 (passenger side) and B1424 (driver side) solar sensor error codes with A/C. Britprius kindly advised:

"The AC faults that have appeared are not really faults. These show up if the windscreen is in the shade or indoors with little light shining on the sensors. If they did a check outside with the sun on the screen the codes will disappear.

"The light sensors are there to show how much UV light "heat" is falling on the screen one for each independent circuit inside the car. This information is then used to control the AC compressor drive motor for maximum efficiency."

Hope this helps you too.

John

genius149 · August 31, 2019

54 minutes ago, royoftherovers said:

How long have you had the car and did you buy it from a Trader ?

A couple of (the hottest) months (on record) and no, it was a private sale.

2 hours ago, ColinBarber said:

There are typically two sensors, one for AC and one for the auto lights.

Having looked at it in daylight, there's the front sensor which is probably fine but if I can get it out to clean and test it, I will. The rear, which is in the corner of the left hand speaker (correct me if I'm wrong) has the sensor cap wedged right between the glass and the parcel shelf so something's definitely afoot there. Annoying because it's probably a nightmare to get to - any advice on how to get to it gratefully received!

Do I need to be looking at the room temperature sensor as well? There are some conflicting opinions in this thread and whilst I can see the "Solar sensors have nothing to do with AC" logic, my research into other threads regarding air con and the fault codes I have make me come to the conclusion that the solar sensor does have something to do with it.

Edit: just read your post John and that makes a lot more sense.

I ought to add, that I've checked all the fuses and they are all ok and that the revs change when the AC is on so that's good too.

Edited August 31, 2019 by genius149
recent post

Britprius · August 31, 2019

Basically as has already been said these codes will always show if the car is checked for faults indoors or in the shade. This applies to virtually the complete range of Toyota/Lexus cars with AC.
This is normal, and should be disregarded as it is seldom a genuine problem. Even if the sensors are faulty they do not stop the AC from working completely.

Take the car to somewhere that really know what they are doing with AC systems. I'm sorry but that does not include Halfords in my opinion.

Can you hear a definite click under the bonnet as the AC is turned on, and off often with a noticeable loading of the engine? If not it is likely that for some reason the clutch to the compressor is not being activated. This can be checked by seeing if there is a 12 volt supply to the compressor clutch Or by putting a 12 volt supply to the clutch "at witch point you should hear the clutch click in" and starting the car. Only do this for a short period, but if the AC works the problem is with the feed to the clutch. If the AC does not become cold the problem is likely with the compressor, pressure switch or gassing.

John.

Texas · August 31, 2019

For info Here's a thread that I posted a while ago when I had VSC problems.

plexus914 · September 3, 2019

On 8/31/2019 at 12:07 PM, genius149 said:

A couple of (the hottest) months (on record) and no, it was a private sale.

Having looked at it in daylight, there's the front sensor which is probably fine but if I can get it out to clean and test it, I will. The rear, which is in the corner of the left hand speaker (correct me if I'm wrong) has the sensor cap wedged right between the glass and the parcel shelf so something's definitely afoot there. Annoying because it's probably a nightmare to get to - any advice on how to get to it gratefully received!

Do I need to be looking at the room temperature sensor as well? There are some conflicting opinions in this thread and whilst I can see the "Solar sensors have nothing to do with AC" logic, my research into other threads regarding air con and the fault codes I have make me come to the conclusion that the solar sensor does have something to do with it.

Edit: just read your post John and that makes a lot more sense.

I ought to add, that I've checked all the fuses and they are all ok and that the revs change when the AC is on so that's good too.

If you wanna change the thermistor cooler sensor (88625-47031) in the rear, you do it like this. See pic 2. That sensor looks like the one I replaced on a 1997 LS400.

https://www.ebay.de/itm/8862547031-Genuine-Toyota-THERMISTOR-COOLER-88625-47031/182382063434?epid=654857084&hash=item2a76d16f4a:g:KqcAAOSwfRtcbS5u