Volvo 850 AC Compressor wont Activate

alexk243 · Post by **alexk243** » 18 Apr 2012, 11:55

So took it to a AC shop to get it tested. Figured I should know for sure (even if it cost $30) that there is a leak before I get into it.

They confirmed that there was 0psi in it. They filled it up to check for leaks and... it held... for now at least. Compressor running and everything. It works. They put in 2lbs of r134 and dye so we can find the leak if it leaks.

What are the chances it will hold?

alexk243 · Post by **alexk243** » 18 Apr 2012, 13:18

Answered my own question. Started leaking withing 30 mins. Proved to be from the Evap Core, but at least I know everything is wokring now.

So to get onto fixing it. The issue I am running into is getting a vacuum pump and manifold set. No one rents them anymore and I would spend $160 on them plus shipping.

Does anyone know of any other solution to evacuating the AC system and recharging it that does not involve me buying $160 in tools?

Also on Volvo 850s is there only a low side port? No high side port?

Post by **erikv11** » 18 Apr 2012, 23:00

People often recommend the Harbor Freight pump and manifolds for one-time AC charges like this, did you check pricing there?

When I was going to do an AC evac and charge myself, I kept an eye on Craigslist. You will see the Harbor Freight tools going for too much there, but occasionally a quality manifold set comes up for $50. Ended up getting a mechanic in a regular shop to do it cheap as a side job though, so I didn't buy anything.

No high side port on an 850.

I'd for sure get a new expansion valve, and likely a receiver/drier too, while you have the system open. There is a good post somewhere on this site about which PAG oil and how much, based on the serial number on the compressor.

alexk243 · Post by **alexk243** » 18 Apr 2012, 23:39

Yea someone posted it in this topic. Great Reference.

They are about $110 for a pump and $55 for a manifold set. There are some cheaper on ebay, but I am not sure about them. Some include air pumps attachments that are suppose to create vacuum... every heard of those or if they work?

Post by **MoVolvos** » 19 Apr 2012, 02:43

alexk243 wrote:Yea someone posted it in this topic. Great Reference.

They are about $110 for a pump and $55 for a manifold set. There are some cheaper on ebay, but I am not sure about them. Some include air pumps attachments that are suppose to create vacuum... every heard of those or if they work?

I hate to say spoil this Post but you do not have enough theory to do the work besides it is illegal to vent the stuff into the atmosphere even if have the vacuum pump and gage set. You should have a recovery tank for that purpose. Once you have that Nightmare dash apart and you are unable to successfully take care of the Evap properly you will have to have it towed to the shop.

Find a local Indie who will work with you on price instead of tackling it unless you are confident you can undertake to understand basic HVAC theory. It is one thing to buy a can and charge it and another to take a whole system apart as you will need to replace the filter dryer and be very careful not to introduce contaminates into the system so it clogs the Orifice/TX Valve. It can be exciting to save a ton of money and take things apart but when it is not successful... Again, hate to rain on this post/parade but somethings are better left to professionals.

Blessings,
BKM
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alexk243 · Post by **alexk243** » 19 Apr 2012, 08:18

Well there is nothing to vent into the atmosphere as the shop informed me that it is completely empty after they detected the leak in the evap core so the vacuum would be there simply to remove contaminants/atmosphere air. The system has already illegally vented to the atmosphere since it was leaking real bad... so the vacuum is only to clear out after the repair is done and the manifold set is simply a way to shut of the vacuum pump and connect a recharge bottle of 134 without opening the system up to the atmosphere, the gauge set then helps out in making sure I have the right pressure in the system (about 1.6 to 2lbs it sounds like, not PSI, but lbs of refrigerant).

I'm not sure I am going to do it as I still have not found a cheap solution to the vacuum pump and I thank you for your concerns on this, but worse case scenario is I take the dash off and I cant do the job... I put the dash back on and drive it to the shop.

The reason I am asking so many questions is so that I can be sure I have all the knowledge, tools, and parts to complete the job before I even get started.

Post by **erikv11** » 19 Apr 2012, 10:09

Yeah, the evap job is long but not very difficult, if you can keep track of where things go and follow an illustrated instruction manual then there is no reason to worry about that part of the repair. It is a hassle, sure, but also a great opportunity to shore up the dash mounts.

I did consider the attachments that use a source of compressed air to create a vacuum, and from what I read they do not work well at all.

FWIW here is what I decided: I have to do an evap core on a Dodge later this spring, once I get the core swapped I am just going to take it to the shop for the evac and recharge part of the repair.

Post by **tjts1** » 19 Apr 2012, 10:52

alexk243 wrote: Does anyone know of any other solution to evacuating the AC system and recharging it that does not involve me buying $160 in tools?

Also on Volvo 850s is there only a low side port? No high side port?

You need a vacuum pump to bring the system down to 30" (perfect vacuum). When I replaced the compressor on my MB I rented a vacuum pump locally but in the future i'm going to build one like this.
http://www.instructables.com/id/Making- ... cuum-Pump/

If you really want to DIY this job, here's what you're going to need.
O rings
https://www.amazon.com/O-RING-ASSORTMENT ... 102&sr=8-2
A new filter dryer. Only install it at the very end of the job. You want to expose it to the atmosphere for the shortest time possible.
Gauges and hoses.

Replace all the O rings in the system that you can access, replace the evaporator, replace the dryer then before re installing the dash vacuum down the system to 30". Once its down to that level keep the vacuum pump going for another half hour. Turn it off and wait over night. If it holds that level of vacuum, congratulations you have no leaks. You might also consider replacing the PAG 100 oil in the AC compressor.

Post by **MoVolvos** » 19 Apr 2012, 14:37

alexk243 wrote:Well there is nothing to vent into the atmosphere as the shop informed me that it is completely empty after they detected the leak in the evap core so the vacuum would be there simply to remove contaminants/atmosphere air. The system has already illegally vented to the atmosphere since it was leaking real bad... so the vacuum is only to clear out after the repair is done and the manifold set is simply a way to shut of the vacuum pump and connect a recharge bottle of 134 without opening the system up to the atmosphere, the gauge set then helps out in making sure I have the right pressure in the system (about 1.6 to 2lbs it sounds like, not PSI, but lbs of refrigerant).

I'm not sure I am going to do it as I still have not found a cheap solution to the vacuum pump and I thank you for your concerns on this, but worse case scenario is I take the dash off and I cant do the job... I put the dash back on and drive it to the shop.

The reason I am asking so many questions is so that I can be sure I have all the knowledge, tools, and parts to complete the job before I even get started.

When the system is at 0 psi it still has R134a just not under pressure. Unless the system has opened the exchange between outside air and R134a at 0psi should be negligible so it is still 134a in the system unless the compressor has gone into suction pressure (below 0 psi) thereby drawing in outside air.

When the system leaks it is neither legal nor illegal but when you draw a vacuum the remaining 134a is vented unless you have a recovery tank. Many HVAC mechanics like many alignment mechanics are R & R guys and follow a protocol but have not studied HVAC nor Suspension Dynamics and Theory. I am not discouraging you but I am providing a sounding board so you do not get over your head and wind up costing you more. I have and I am sure others at one time or another wished someone had told me so but didn't.

Blessings,
BKM
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Post by **erikv11** » 19 Apr 2012, 20:47

There is a hole in the core, so the system is at atmospheric pressure which means the R134a has all completely vaporized. It boils at -15˚ F. Through that hole there is free gaseous exchange between the air and the system, which means that very quickly all of the R134a will be evacuated. There is no R134a left in the system, so none will escape when a vacuum is pulled.

You have to choose: legal or illegal. Must be one or the other. Can't be both, can't be neither. From all I have read, the actions discussed here are all entirely legal.

I hear you on the warning and sounding board, IMHO a good discussion includes hearing what may seem to be the devil's advocate, so you are really helping out the OP and others who will read this thread down the road.

Volvo 850 AC Compressor wont Activate

Re: Volvo 850 AC Compressor wont Activate