Hi, it´s been a while since my last post. My wife´s 96 854 T5 electronic climate control system has been acting up. It´s been very very hot here in Argentina lately, about 40º celsius last week.

The blower works fine, but most of the time all I get is hot air. Suddenly cold air starts coming out, and after 10 minutes it stops. If I put the A/C switch (the one on the right) in OFF, wait a while and then turn it back on, sometimes I get cold air for another 10 mins or so.

This is my wife´s car and as you can imagine she´s driving me crazy about the problem.

Any ideas? Maybe a faulty relay? How do I force the compressor on to see if it´s working correctly.

Regards
Axel

 

Axel, it sounds like your compressor is low on freon, thus causing the compressor to 'freeze' (almost quite literally). I'm not sure what your auto parts places are like in Argentina, but you can buy cans of R134a and add them to the low pressure side of the a/c system and a lot of times that will hold you over. More than likely, the leak in the system is coming from the evaporator. - AB

 

Concur. Mine was doing the same thing. I have a small leak, but if I re-charge the Freon from time to time, it seems to work fine.

Good luck

 

Hello Axel,

Greetings from Chicagoland, U.S.

850's have a notorious compressor that shuts down when you most need it. 50% the time it's the low refrigerant (R134a), but another 50% is the compressor itself. There is a thermal/pressure switch that shuts the compressor off, and there are two wires that have to be jumped, in order to bypass this switch.
I used re-charge kit, and the gauge on the kit indicated OK, even though I had the same problem as yours do.

I'm sorry that it's 40C there, it is HOT!

Good luck,


JPN

 

How do I measure the freon pressure to know if there is a leak?

 

The Best thing to do is have the System evacuated and recharged with dye.
Then have the compressor gap checked. Min is .020 thousands.

If it is over that then there is a chance the Clutch/compressor is bad.

 

But would that be consistent with this?

"If I put the A/C switch (the one on the right) in OFF, wait a while and then turn it back on, sometimes I get cold air for another 10 mins or so. "

 

If my car isn't blowing cold air, but can blow hot. Do I need a freon recharge, or do you think something is wrong?

Btw, is there any way to clean out the air system, there seems to be a lot of dust and crap in there...

 

Sounds like a bad compressor or the system is freezing up.
When it starts blowing hot check for power at the single wire at the compressor. If you have power the Clutch/compressor is bad.

 

^How do I do that/what does that mean?

 

I've been monitoring the A/C for the last 10 times someone has used the car. After the car hasn't been used for about half an hour and the car is started, the A/C works fine approximately for the first 20 minutes. Then cold air stops coming out, but the blower still works. Turn the A/C off for 10 minutes and turn it back on, and I get cold air again for a while. The behaviour is always the same.

So now I have 2 questions:
1) If the freon pressure is low, would I still get very cold air when the system is working? (less freon = less cold?) Is the cold proportional to the freon level?
2) If the system is freezing, where should I look to check? When I bought the car, the component in the attached picture used to freeze, and Tech told me to change the low pressure switch, which I did. Now it does notfreeze anymore AFAIK. What other component should I check for freezing?



[IMG]local://upfiles/4713/5F28EB5468A34B12AF916D2D05B39400.jpg[/IMG]

 

Hello Axel,

1):In general, yes, the more refrigerant (R134a) you have, the colder the air. However, as long as you have above minimum level of R134a, the air temp should not change much IAW the level. You still get cold air even if the R134a is low, though the compressor would turn on & off repeatedly. This is not a favorable situation, as low refrigerant means low lubricant as well (lubricating oil is mixed with the refrigerant and is circulating in the system with it).

2): The cylindrical item is the receiver/drier unit. This unit acts like an accumulator for the refrigerant (R134a), when the A/C is not used. When the A/C is activated, it filters out any moisture that is in the system. Evaporator could freeze too. Evaporator collects moisture due to condensation, especially in damp weather. In 850, the evaporator is deeply embedded in the dash, and much of the dash has to come out in order to gain access to it. Many other cars have it behind the glove box, which makes it easier to inspect/remove.

Usually, many cars have sight-glass where you can visually check the refrigerant level, but for some reason 850 doesn't seem to have one. Anyway, a system with good refrigerant charge is indicated by clear glass, with small bubbles flowing through once a while. Near empty system shows many bubbles, and an empty system does not show anything.

An aftermarket re-charge kit usually comes with a gauge that tells you if the system is at correct charge. I used one, and even though the level was in the green band (full charge), the compressor kept turning on/off, so one of the wires on the compressor has to be jumped in order to bypass this notorious switch.

I wonder if I answered your question.


JPN

 

JPN,

Thanks for the info. Looks like the A/C design is subpar. No sight glass? No easy access to the evaporator? Probably a factory-designed dead end for users so they have to visit the stealership.

More questions:
1) Is there any way toknow if the evaporator is freezing without removing the dash. I know it's necessary if I want to replace the evap, but maybe there is some other indication that will tell me if the evap is freezing without all that work and risk of breaking additional parts.

2) Why would lowR134a cause freezing? I understand why a pressure switch would be triggered, but I don't understand the freezing part of the story.

3) Isn't it risky to bypass the compressor pressure switch? I suppose it's protecting the compressor from possible overheating from lack of lubrication due to low freon/lubricant. I don't want to risk losing my compressor.

Regards

 

Hello again Axel,

Yes, 850's A/C is of very poor design. In Sweden, A/C may not be a necessity and I wonder if it's part of the reason. But the compressor on my 850 is made in Japan, by mfg I've never heard of (Usually Japanese mfg's use Denso or Keihin compressor).

As to more questions:

1) Take a look at the image named "Exp Valve" (If I posted it correctly). This little valve "sprays" R134a into the inside the evaporator, so that R134a absorbs heat in the cabin and cools down the evaporator. As you can see in the image, there is a temp-sensing probe and this should prevent the evaporator from freezing.Unless your A/C keeps running out of refrigerant, the evaporator is probably ok. 850 seems to have notorious evaporator that gets corroded due to moisture collecting on the bottom of the housing.

2) Low refrigerant level shouldn't cause freezing, unless something is wrong. This is beyond my guess at the moment. In theory, too low a pressure causes freezing, so there may be a restriction within the system that is causing low pressure at certain location. I need to study more on A/C myself, I may buy a book on automotive A/C system. You may need a new receiver/drier unit, but ask A/C expert before spending money.

3) Indeed, it is risky but the compressor on 850 seems to be of poor design to begin with (I'm ashamed as a native of Japan). But since 850 is an old car (though modern cars should go over 20 years/300,000 miles ifan owner takes good care and follows scheduled maintenance), the compressor may be getting old too. I wonder if there is a compressor made by reputable mfg (ex: Denso) that can fit 850, otherwise you may have to go with that OEM.

I also embedded an image of receiver/drier with a sight glass on it. If I posted it correctly, you can see it.

I hope this answered your question.


JPN

[IMG]local://upfiles/6892/AF515D7EF9534BA190782D7A9C041E15.jpg[/IMG]

[IMG]local://upfiles/6892/EC17592406E24F409F0E54F25008346A.jpg[/IMG]

 

I will bet the compressor clutch is STILL bad.
It acts exactly like the clutch is bad and disengaging when it gets hot.
Find the single wire going to the compressor. If you follow it all the way it will lead to the clutch on the compressor.
When it stops working hook the Test light to ground and probe that wire. If you have power the Clutch is bad.
Also if you have power the clutch is an electronic magnet.
Then Very carefully tap the clutch with a Stick or long screw driver and see if it starts working again.
I will bet it will.

If you want to try to fix it your self check out the link to my post.
https://volvoforums.com/m_34431/tm.htm

 

Today I took the car to an A/C guy and he told me that there was a faulty ground on the A/C relay that is behind the glove compartment. He said he'd seenthe same thing happenbefore on an S40, which does not have the relay behind the g/c, but it's in the engine compartment.

He said that after identifying the wires on the relay, he replaced the faulty ground cable with another ground source and that everything should work great now. He also said he measured freon pressure for an hour, and that there were no leaks. He charged me U$ 50 for two visits to his shop.

I'm crossing my fingers now since I have to travel 800 kms this weekend and it's 35 celsius out here during Dec/January.

I'll post here if this doesn't work. Thanks for all your help.

Regards
Axel

[EDIT]
I've seen a lot of corroded wires on this 11 year old car. I have a 97 Hyundai and my dad has a 98 Mitsubishi. We've never had any problems with corroding cables. Is this a usual problem with Volvo's?

 

Update: my wife drove the car for 10 minutes and the A/C failed again. #$%^#$%^#$%^#$%^I'm sick and tired of this POS car. Wht is everything so complicated and over engineered?

 

Take it back to the guy you gave the $50 to. Anybody that only charges you that much and actually did something has to be pretty honest.

I think they should force engineers to work on cars. Then they might design them easier to work on.

 

I called the A/C guy and he asked me to take the car back tomorrow at 8AM. That will be the third visit and about 30 days melting without A/C. I am pretty much hating this car because of the time I am spending on details that are hard to solve.

The funny thing is that the last time I went to the stealership, the guy that works there told me not to get it fixed at the stealership because they will just try to throw parts at the problem. He told me to go to a shop that specializes in A/C because it would probably get fixed without buying any parts.

 

Hello Axel,

I'm sorry that your A/C problem hasn't been solved yet. I would follow Mr. Tech's advice, rather than that A/C guy who didn't solve the problem.

Again, the compressor is notorious for turning on/off repeatedly. There seem to be two solutions:

1. Jump the wire to bypass temp switch that is shutting down the compressor.
2. Replace the compressor.

Yes, Volvo's are over-engineered and I myself hate the way they designed self-diagnostic functionthat renders the car useless with negligible faults.

If you are afraid of overheating the compressor by bypassing the temp switch, you can install a small cooling fan to direct cooling air at the compressor. A PC cooling fan seems ideal for this, but you'd have to do all wiring & installation by yourself.

If good care is taken and proper modifications are done, I believe Volvo's are still excellent cars. Sadly, most people I know never follow scheduled maintenance and wait until something breaks, by that time something else is also affected.

Anyway, try the above if you feel like. I think this compressor & the ABS module should have been factory recall items because they are obviously defective to begin with.

I wish you the best.


JPN