DaveK

OK - I got the 4-seasons receiver / dryer which was mentioned in another thread. I fitted it this evening - the connectors look right, and it fits. But.....

The flow sticker is the opposite way around. The one I took off has the flow sticker pointing away from the pipe which comes from the condensor (i.e the one at the front of the car), and it also has IN stamped by that connector.

The rec / dryer I put on has the flow sticker the other way around - so pointing towards the condensor connector (didn't notice if it was stamped as well, because I only noticed the stamp on the old one when I'd finished).

I'm sure I've been sent the correct part number - but why is the flow direction important? Does this mean the rec / dryer won't work now? Will I die a slow horrible death from poisonous gases if I try to use air con once it's recharged?

I know some people have used 4-seasons receiver dryer - so was yours also the wrong flow direction?

gfunk

Dave,

I used the 4-seasons part and it worked fine. I didn't notice any flow directions, I just assumed it was correct. I would go ahead and try it. It's a closed system, so provided you don't have any leaks you won't have any problems breathing freon.

Greg
89 C4

springer3

The flow direction is important. There is s tube that draws from the bottom of the receiver chamber. One function is to help separate gas and liquid phases in the compressed freon. When you see bubbles in the sight glass, it is because the receiver is nearly empty, and the tube is picking up two-phase freon (you want only liquid phase at this point in the cycle).

If you install the receiver dryer in reverse, you will still have some cooling, but because you are not separating the gas and liquid phases, you lose capacity. You might be OK in Vancouver and the UK, but in the southern US, we need every BTU we can get (funny we still use the British Thermal Unit decades after the British abandoned it).

I would send the thing back and get he correct one.

gfunk

Springer3,

You could be right about the direction, but after installation my air conditioner blows cold air near the bottom of the specification range. Perhaps it won't work as well if the freon starts to leak out.

Greg
89 C4

gfunk

Dave,

Here is the recevier/dryer I installed. It appears to be installed correctly with the "In" port connected to the condensor. I ordered 4-seasons part #R1040-89421 but I didn't see any numbers on the actual part so it is possible they substituted something else.

Hopefully this helps.

Greg
89 C4

DaveK

Hmmm- yours is silver, mine was black. In addition, on the order it said it has a sight glass - and the one I received doesn't. I am now thinking I have been sent the wrong one after all. Which is a pain, since it came from the States, and the postage was more than the part.

DaveK

OK - I think I know what has happened. On the bottom of the rec. / dryer I was sent the part number sticker says : 40033278. Four-seasons rec / dryer part numbers (at least in the UK) start with 33 - so if I type 33278 on their page it comes up with a Honda Civic receiver / dryer. The connectors look the same as the Porsche part - although slightly shorter (the Porsche ones seem to have a "nut" behind the thread part which makes it a bit longer). However - the part number 4-seasons UK gave me is 33821 - which does have the longer connectors.

So - what I think is, I've been sent the civic part. In addition, this suggests that the Honda receiver dryers are not exactly the same part because the flow direction is the wrong way around even though the fittings look the same. Although I know that the website I was initially given for the 4-seasons part did list the same part for Honda and Porsche. But 4-seasons themselves don't.

springer3

Greg:

The flow arrow should point to the line that goes to the expansion valve and evaporator near the passenger compartment. Are you sure you have the backwards receiver/dryer?

The receiver/dryer, as the name implies, has two functions. It contains a dessicant to remove any water that got left in the system. The "receiver" function means it receives the two-phase (gas and liquid) high-pressure freon from the condenser. The function of the receiver is to provide a volume to separate the liquid and gas phase by gravity. Two-phase mixed flow enters at the top. The liquid goes to the bottom, and the lighter gas phase goes to the top. The same thing happens when you pour beer into a glass. The liquid goes to the bottom, and the foam goes to the top.

The exit line from the receiver is connected to a tube that draws only the liquid phase from the bottom of the receiver. Liquid freon goes to the expansion valve, where the pressure is dropped. The liquid boils back to the gas phase as it travels through the evaporator. "Angel's breath" is produced when the cabin air is blown through the cold evaporator. A properly charged system has cold gas at the compressor suction, hot gas at the compressor discharge, hot two-phase flow in the condensor, hot liquid going to the expansion valve, and then cold two-phase flow in the evaporator. A critical step in the process is separation of the liquid and gas phases in the receiver.

If your receiver really is backwards, the two phase freon enters through the tube at the bottom. Gravity separation will still occur, although the fresh freon entering at the bottom will certainly keep things stirred up. You will still have mostly gas phase at the top where the incorrect "discharge" port will send mostly vapor to the expansion valve and evaporator.

There are only two ways you could be getting good cooling:

1) It is a relatively cool day, so you are not operating near capacity

2) Your system is so over-charged that the condenser is already fully liquid before it reaches the receiver dryer.

In the second case, you are operating with very little gas cushion in the system. The compressor discharge pressure is way too high. You risk bursting a hose or damaging the compressor. You will certainly consume too much engine power for the cooling you are getting.

If you still don't believe me, get your system on a set of pressure gages and read the system pressures. With the receiver in backwards, you will have high compressor discharge pressure and very low system efficiency. You live in a cool climate, and you have a system designed for Saudi Arabia. If you want to take advantage of the system's high margin for your climate, that is fine with me. However, the AC compressor is very powerful, and capable of extremely high pressure. It is quite dangerous to abuse powerful equipment. Please refrain from encouraging others to install backward parts. Somebody could come to grief.

DaveK

Springer3,
Greg's photo shows that his seems to be the right way around, so I guess his is OK. I should have the same part - but it looks like I don't. Funnily enough though - the connectors on Gregs look like the part I was sent (fairly short) and not like the one I took off (a bit longer) and not like the Porsche part on the 4-seasons web page. But - his is stamped with "In" and mine isn't, so I guess his is OK.

Your explanation of what the receiver / dryer does is excellent and makes a lot of sense. I had assumed it was only a "drier" and couldn't understand why direction mattered - but now it makes sense.

I think I am going to give up with the 4-seasons part and order OEM. It will cost me more in the long run but since I'm in the UK it looks like the simplest bet.

Thanks a lot for your help.

gfunk

Springer3,

I stand corrected! Your previous post did get me thinking which is why I went and checked that my receiver was installed correctly.

Thanks for great explanation of the cooling system.

Dave - Sorry to hear you need a new part...

DaveK

Greg,
Did yours have a sight glass on it? Mine didn't. I am still confused a bit, because although the places you can order it from list the same part for 964 & Honda Civic, 4-seasons don't. Your's looks like the connectors are the same as the one I was sent - and yet, yours is the right way around and mine isn't.

How long ago did you get yours?

springer3

Thank you! I have taken a lot of great information from this site, and I am glad if I can make a contribution.

gfunk

Dave,

I ordered my receiver from 911autoparts.com on June 15/04. It looks from the picture I took that it has a sight glass but I never paid any attention to it.

DaveK

Greg,
Sorry for another stupid question :

Is your system still R12, or is it R134? I just spoke to 4-seasons UK - they said it (might) have the wrong sticker on mine - but no way to confirm - but they also said that I don't have a sight glass because it's a R134 part, not R12. They were doubtful that the part I've been sent would fit the car if it's the wrong one.

gfunk

I converted my system to R134. I always assumed that the receiver I have is compatible with R134 but there was no explicit documentation. In any case it seems to work fine for now.