Interesting a/c problem/solution?

[oddjones]

My T5-R aircon never worked, and when I called up a local specialist he told me that 850's were prone to chewing up evaporators - an expensive business, coz they're behind the dashboard, so a replacement is time consuming... I don't know the truth of this myth, but when I bought my T5, my heart sank when the aircon kept cutting out after 5 minutes.

There's a bloke in my street who does re-gassing, so I had a chat with him and he agreed to come and have a look... He checked the system over for leaks and said that it looked good - regassed it and all seemed well - until 5 minutes after he restarted the system when it did the exact same thing to him... cut out after 5minutes. In the course of much head scratching and general poking about he disconnected one of the pressure switches (circled in the picture below) and nothing happened. So we switched the system on again and lo and behold... it worked fine (so far). It may have been that there was simply a dirty contact on the pressure switch and simply disconnecting it and reconnecting it has solved the problem... I'll keep you posted if it breaks again, but it's certainly worth considering before making expensive repairs...?

http://www.oddjones.com/project_hearse/images/enginebay.jpg

[Adge]

Thanks for that. Air-con specialist undertook to replace my evaporator, started, saw what was involved and put it back together again!
I'll try your thing just in case, but I'm not too hopeful!

[Adge]

No such luck-suppose I need the evaporator after all. Will have to bite the bullet! Local dealer are supposed to have asked Volvo if they'd contribute towards the cost. No such luck! 1998 and only 62,000 miles as well! Grounds for complaint?
Had P18000, 240 GLT, 740, 745 and known for build quality and reliability. Have Volvo joined the cut-corners/reduce quality brigade now, or is this a one off!!?


My T5-R aircon never worked, and when I called up a local specialist he told me that 850's were prone to chewing up evaporators - an expensive business, coz they're behind the dashboard, so a replacement is time consuming... I don't know the truth of this myth, but when I bought my T5, my heart sank when the aircon kept cutting out after 5 minutes.

There's a bloke in my street who does re-gassing, so I had a chat with him and he agreed to come and have a look... He checked the system over for leaks and said that it looked good - regassed it and all seemed well - until 5 minutes after he restarted the system when it did the exact same thing to him... cut out after 5minutes. In the course of much head scratching and general poking about he disconnected one of the pressure switches (circled in the picture below) and nothing happened. So we switched the system on again and lo and behold... it worked fine (so far). It may have been that there was simply a dirty contact on the pressure switch and simply disconnecting it and reconnecting it has solved the problem... I'll keep you posted if it breaks again, but it's certainly worth considering before making expensive repairs...?

http://www.oddjones.com/project_hearse/images/enginebay.jpg

[nobananas]

I am looking at a brand new evaporator in a box on top of my wardrobe which is waiting for me to bite the bullet and fit it ! ( I have had it for about a year now !) Yours certainly isn't a one-off but you have to remember cars of old often didn't have air-con or half of the electronic muppetry of today so they're bound to be more reliable !

[splatt]

Had the same prob on an old car. The circled bit is the low pressure sensor, cuts the aircon when it thinks there is insufficient AC coolant for the pump to circulate.
About £12 from Volvo!

[oddjones]

Works for a bit then bombs out again - It's supposed to be hot this weekend too... Sorry splatt, are you saying that changing the switch fixed the problem? If so then that's a total bonus...

[splatt]

yes, it did fix the prob but you have to remember the 850 AC is flawed and leaks like a cheap nappy.
Take the low pressure switch off, as you release it there should be a puff of AC gas (self sealing valve) give it a good clean and try again....
If it does not work then it has to be someting more sinister... :(

[T5SLAVE]

Excellent info/thread oddjones:)

My aircon has been overhauled/re-gassed but is still (4 want of a better word)...PANTS! I will investigate this lil' switch thingy when I get her back next week...until then I'll keep my pinkies crossed it's that n not the evaporator, here's hopin:confused:

[oddjones]

yes, it did fix the prob but you have to remember the 850 AC is flawed and leaks like a cheap nappy.
Take the low pressure switch off, as you release it there should be a puff of AC gas (self sealing valve) give it a good clean and try again....
If it does not work then it has to be someting more sinister... :(

When my guy regassed it he took out about 600grams of gas (or something like that - I honestly wasn't listening very hard) - which he said was good as he only put back in 750-odd, and he said that there are no leaks as I would've seen flourescent green stuff coming out... When you say "Take the low pressure switch off" - does it unscrew with a spanner? (I can see you're all really impressed with my level of technical detail here) - All my guy did was pull out the electrical connector on top and give it a quick brush - I'm just a wee bit lary of unscrewing it and watching a cloud of flourescent green gas disappear out of my (currently partially working) system, but equally lary of taking it to an Air Con specialist and having them suck their teeth at me...

[spencem875]

Tried that fix and still same. So odd my AC. Went from my house to shopping centre (20-30 mins away) and stayed ice cold all the way. 45 mins go back to car to go home and nothing. Some days im lucky to get 5 mins, some others are longer.

[splatt]

When my guy regassed it he took out about 600grams of gas (or something like that - I honestly wasn't listening very hard) - which he said was good as he only put back in 750-odd, and he said that there are no leaks as I would've seen flourescent green stuff coming out... When you say "Take the low pressure switch off" - does it unscrew with a spanner? (I can see you're all really impressed with my level of technical detail here) - All my guy did was pull out the electrical connector on top and give it a quick brush - I'm just a wee bit lary of unscrewing it and watching a cloud of flourescent green gas disappear out of my (currently partially working) system, but equally lary of taking it to an Air Con specialist and having them suck their teeth at me...13 or 14 mm spanner, quick puff of gas as self sealing valve, screw new one back or clean old one up properly. :)

[oddjones]

Took it off & cleaned it as suggested last night and my a/c worked for a whole 4 hours! Went to volvo & ordered a new 'un this morning (£35 now tho Splatt - don't know how long ago you bought yours?) - Arrives tomorrow so we'll have to wait and see....

[spencem875]

Took it off & cleaned it as suggested last night and my a/c worked for a whole 4 hours! Went to volvo & ordered a new 'un this morning (£35 now tho Splatt - don't know how long ago you bought yours?) - Arrives tomorrow so we'll have to wait and see....


1. How did you clean it?
2. Mine makes a strange smell just b4 the AC stops working, does yours?

[woz]

Could be the clutch on the compressor?? It is electrically operated and cuts in when the sensors say "More cold air needed". You can hear it cutting in and out when idling, with associated rise in engine revs. If stuck - which happened to me - you get no compressor, no a/c. You can clunk the pulley gently to try to free it up. Hope thats not the prob as it means a new compressor I was told!

Also - is you four stage fan working corrrectly? The controller for that went on mine and the a/c stopped working then too.

CHeers
Woz

[oddjones]

Replaced the pressure switch this morning and everything seems good - To be honest there's not much to clean inside it - it's just a hollow chamber with a small hole which leads up into the body of the switch itself. For anybody else struggling to get their ac working (and let's face it - today, if your ac isn't working, you're going to try pretty much anything!)... the way to diagnose this issue (botched from what I learned from my ac guy) is this...

When you turn the AC on, as the evaporator gets colder there's a change in pressure as the gas cools - this takes between 5-10 minutes. The pressure switch erroneously reads this change in pressure as there being no gas in the system, so cuts the compressor. If you turn the ac off and leave it for another 5 minutes and allow the pressure to change back and turn the AC on it will work again (for another 5-10 minutes) - This cycle seemed to work for me every time which suggested it wasn't a goosed compressor clutch, which would (to my mind) give progressively poorer performance as you went on turning the ac on and off...

Still, it's early days yet - I'm not saying it's FIXED, but it seems to be working at the moment.

The strange smell? - no, but apparently the main cause of smells from AC (again, according solely to my ac guy - I'm no expert) is dead flies and leaf mulch getting into the system and going bad (niiiiice)

[T5ER]

LOL tried to do it with my a/c mate but made no difference at all,so still no a/c

[nobananas]

I did find with mine that for the couple of hours that I was holding gas for (knackered evpourator) my air con still wouldn't work. When the aircon was engaged I was getting power to the a/c clutch but it wasn't throwing in. If I gave the clutch a direct feed from the battery it would come in immediately. The reason is obviously a worn a/c clutch (the gap was too great for the electromagnets to pull the clutch plate in) but with a current boost i.e straight off the battery it would work fine. I remedied this by wiring in a 30 amp switching relay to the clutches switched live and hooking up the other direct to the battery using a fairly meaty wire and a sutable in-line fuse holder. This worked fine for a good few hours until all my lovely gas had gone ! Incidently, you can re-shim the clutch clearances on some a/c clutches to decrease the gap and you can also replace just the clutch mechanism seperately from the a/c pump ( clutch just knocks off) but some dealers don't give you that option unless you ask for it.

[spencem875]

Cleaned that switch, lets see what happens tomorrow.

[monkey_boy]

Sounds almost exactly like my symptoms. Although I have a C70. I know they share a lot of parts with 850's but surely by 2000 Volvo should have sorted this out?

[spencem875]

Seems to be working more often now, any idea what the part no. is for that switch?

[lighterfuel]

I also have had a problem with My 850 T5. The A/C works fine for 5 mins and then a strange smell and then warm air blasts out causing condensation in the cabin. Hands slide on the steering wheel....GROSS!

I tried taking the fans off AUTO and the same on the Fan direction AUTO setting. So I just had the fan speed slider 3/4 of the way to full and the fan directions blowing through the front dash vents. So, NO AUTO anywhere in my settings. What I found was the A/C stayed on for at least 30 mins longer before giving up. I also find that if i pull over and rev the engine to approx 5000RPM the cold air comes back on for another 10 mins or so.

Why does it work if i rev the pants off the engine? and what does this diagnose?

How much would a compressor set me back?, if indeed thats the issue!

Thanks

[oddjones]

Seems to be working more often now, any idea what the part no. is for that switch?

9171700 (pressostat)

[oddjones]

I also have had a problem with My 850 T5. The A/C works fine for 5 mins and then a strange smell and then warm air blasts out causing condensation in the cabin. Hands slide on the steering wheel....GROSS!

Have you considered an exorcism?

[spencem875]

I also have had a problem with My 850 T5. The A/C works fine for 5 mins and then a strange smell and then warm air blasts out causing condensation in the cabin. Hands slide on the steering wheel....GROSS!

I tried taking the fans off AUTO and the same on the Fan direction AUTO setting. So I just had the fan speed slider 3/4 of the way to full and the fan directions blowing through the front dash vents. So, NO AUTO anywhere in my settings. What I found was the A/C stayed on for at least 30 mins longer before giving up. I also find that if i pull over and rev the engine to approx 5000RPM the cold air comes back on for another 10 mins or so.

Why does it work if i rev the pants off the engine? and what does this diagnose?

How much would a compressor set me back?, if indeed thats the issue!

Thanks

Exact same prob as me, except i dunno about the 5000rpm bit.

[NugentS]

A lot of these symptoms sound like mine which is / was the aircon clutch. Mine is worn and cutting out intermittently. I thn eturn the AC off for 5 minutes and it works again when switched on.

Took a hammer to the clutch the other day (well my mechanic did) and he seems to have bodged it into working - but I guess we will see...

Sean

[monkey_boy]

I remedied this by wiring in a 30 amp switching relay to the clutches switched live and hooking up the other direct to the battery using a fairly meaty wire and a sutable in-line fuse holder. This worked fine for a good few hours until all my lovely gas had gone !

Did the fix use the gas or where you low anyway?

Any pictures of the install?

[spencem875]

Coming home from outlaws i had to turn AC off i was freezing. However, on the way there it was working for 5-10 mins, had a turbo urge and booted it abit, funny smell, no AC. Roll on winter.

[woz]

I.....warm air blasts out causing condensation in the cabin. Hands slide on the steering wheel....GROSS!
Thanks

I bet this is heater matrix ! You will have water coming out under your fromnt carpets too - though you cannot see it till you peel back.

Check your coolant level!!!!

The matrix leaks, catches some of what has leaked out and heats it up so water vapour comes out the vents ! Bet it stinks too.

good news is...Its a cheap and easy fix - new matrix £50 tops, two hours farting about to do the job. Get "o" rings in advance as new ones are needed.

Cheers
Woz

[nobananas]

Unfortunately this fix worked for about three days till the gas ran out of my knackered evapourator and the low pressure switch kicked in ! Wiring the relay in is simple. You need a 30 amp switching relay often called an accessory relay. On the top is a small diagram of how the relay works internally. I can't remember the terminal numbers off the top of my head but you will have four altogether. The relay diagram will show two pins connected either side of a switch symbol and the other two either side of a box like symbol. You need to cut the feed wire to the compressor clutch (follow the wiring up to the slam panel and cut it there rather then down by the pump) and connect the end that goes to the compressor to one of the switch terminals of the relay and the other cut end of the wire to one of the terminals connected to the box type symbol. The other switch terminal on the relay needs to be connected via an in line fuse holder to the positive terminal of the battery. The remaining terminal on the relay (which should be the other side of the box type symbol) needs to be connected to an earth (metal part of the cars body) The relay can be mounted up by the radiator to the left (as you view the car from the front) where it can be easily accessable. I would recommend before doing all this that you check for a live at the compressor with the air con on to rule out high and low pressure switch problems then connect a temporary live to it direct from the battery, if it works fine then proceed with the relay wiring. This assumes of course that you know you have gas in the system ! Wiring in this relay will not bypass the pressure switches in any way and the system will work as normally intended, it just helps a tired air-con clutch along !

Did the fix use the gas or where you low anyway?

Any pictures of the install?

[T5Rdragon]

For those in the VOC, there's an article in this months Volvo Technical Driver about the 850 aircon and the evaporator issue. It seems the issue is a piece of equipment called the accumulator, which is basically a large cylinder with a sunstance not too dissimilar to silica gel, used to keep packaged electronics dry - it's purpose it to remove moisture from the air.

The accumulator is meant to be replaced every 3 years or so, else it loses all ability to remove moisture, meaning the compressor ends up trying to compress liquid, eventually destroying bearings and the impeller.

The knock on effect of this is that you will have bits of metal floating around the system, which needs to be fully flushed and an extra nylon filter fitted to catch any remaining particles (meaning you need to have the filter checked and cleaned regularly initially)

So the key to not having the compressors and evaporators dying is to keep on top of the health of the accumulator.

[spencem875]

I decided to chat with my dad who lives in USA about AC prob (he a abit of a car wiz). He says why dont you ring your uncle? im like why??? he says cos hes a volvo technician, im like HAHAHAHA ohreally............

[spencem875]

Right, it seems there is a certain noise from the engine bay when you turn AC on (i assume this is the AC clutch?). Basically AC works when you hear it and dont when you cant. Now, were is this AC clutch? how hard is it to fix?

[woz]

In the back of the pulley on the compressor pump.
I was tod you canna fix it - needs a new unit - £150.
Anyone want to add to this??
Good luck mate.
W

[Babybadger]

In the back of the pulley on the compressor pump.
I was tod you canna fix it - needs a new unit - £150.
Anyone want to add to this??
Good luck mate.
W

I was under the impression you can adjust the clutch gap on the compressor.

[Adge]

For those in the VOC, there's an article in this months Volvo Technical Driver about the 850 aircon and the evaporator issue. It seems the issue is a piece of equipment called the accumulator, which is basically a large cylinder with a sunstance not too dissimilar to silica gel, used to keep packaged electronics dry - it's purpose it to remove moisture from the air.

The accumulator is meant to be replaced every 3 years or so, else it loses all ability to remove moisture, meaning the compressor ends up trying to compress liquid, eventually destroying bearings and the impeller.

The knock on effect of this is that you will have bits of metal floating around the system, which needs to be fully flushed and an extra nylon filter fitted to catch any remaining particles (meaning you need to have the filter checked and cleaned regularly initially)

So the key to not having the compressors and evaporators dying is to keep on top of the health of the accumulator.

Can anyone please tell me if the system on a 1998 C70 a) has one of these
b) where it's located and c) could it be the source of a gas leak.
My second expert is as confused as the first as to where I'm losing gas, so this may be another option!