Automotive Air Conditioning Information Forum (Archives)

bobinyelm on Wed July 03, 2013 9:53 AM

Year: 1989
Make: Volvo
Model: 740
Engine Size: 2.3
Refrigerant Type: R-134a
Country of Origin: United States

1989 Volvo 740

Just retrofitted R-12 system w/ R-134 w/
New Sanden 709 Compressor
New Refrigerant Hoses
New Nissen Condenser
New Accumulator (receiver/Drier)
New Variable Orifice
New R-134 adjustable low pressure switch
All New O-Rings
Replaced pre-charged Mineral Oil supplied in compressor w/ Ester Oil
Wired a relay to run the OEM pusher cooling fan anytime A/C clutch is engaged (especially for Phoenix Summertime use-may disconnect when ambient temps drop below 80 deg F).
Car has engine driven mechanical fan behind radiator, and OEM pusher was temp controlled back-up only previously).

System does NOT have High Side Service Port (Never Did From Factory), but I installed a High Side Port on the Shraeder fitting on the back of the compressor for testing purposes (being at the compressor, I am sure it is oil soaked and will have gross pulsations when system is running).

Can pull full vacuum (29+" on gauge) and will hold for hours, but not overnight when connected to the Low Side port only.

1) How does one set up and evaluate a system w/o a High Side port between the condenser and the orifice valve?

2) Is it advisable to install refrigerant in a system that leaked down over a 12hr period (I plan to add 1-can Leak Stop and Dye, then 80% of the R-12 Fill Capacity of R-134a.

3) I am told that with a Variable Orifice, the traditional gauge pressures running will not be relevant. Is this true?

never did from factorynever did from factory

mk378 on Wed July 03, 2013 10:29 AM

1. Same as any other system. Many cars have the high side port before the condenser. Pressure drop through the condenser should be negligible.

2. Never use a "stop leak" product. If you aren't sure if still leaking, put in a small amount of 134a (up to 50 psi or so) and let sit overnight. If the pressure holds, finish charging. If it doesn't, find the leak.

3. No one here has had good results with a variable orifice. Use a fixed orifice. On some conversions, going one size smaller than stock has helped.

bobinyelm on Wed July 03, 2013 11:44 AM

Oops-

Too late both counts.

On the Volvo Forum, the VOV was highly recommended. I should have come here first.

On the Stop Leak w/ Dye, that was recommended as well. Repeat-Should have come here first.

On the High Side port, I was told that putting the High Service Port on the back fitting on the Sanden was useless since there is too much oil there, and that location is subject to huge pulsations.
They said do NOT hook up a line there as it will fill my gauges with oil that will blow out of the compressor, and which I'll have to replace.

Could you confirm that the place I mounted the Service Port is actually OK to connect my High Pressure gauge to and use (believe) the readings?

For reverence, here's a Copy/Paste Link to where I put the Service Port on the Shrader valve (red arrow): http://screencast.com/t/nieOiOHQ1

Thanks much-

fix_it on Wed July 03, 2013 3:51 PM

In reference to the variable orifice, some say they work and some say they cause more trouble than they help. I've never tried one. Either way, it won't damage the system. The stop leak on the other hand is a huge mistake. There are two types. One type is an "o-ring conditioner". This type will eventually turn all the seals in the system to mush. However, it will flush out. The second type reacts with air. It hardens with a chemical reaction and supposedly seals leaks in metal lines and heat exchangers. However if there is any trace of air in the system, it will harden inside the system. If you ever have to open the lines for anything (or a hose bursts) you'd better already have the flushing tools in hand or it will ruin every part of the AC system. Once it hardens, it can't be removed.

What kind did you use?

NickD on Wed July 03, 2013 4:16 PM

TI took over the rights to see if they can improve on the VOV, after wasting a bunch of money, they couldn't. Guess its not easy to control pressure with uncontrolled pressure. But not much different in principle than a TXV, there, they are controlling pressure with temperature.

Can see a very strong advantage to not have a high side service port, no high side service port to go bad. But using a thermometer at the outlet of the compressor and a P-T chart would get you close. No more HPCO switches on these newer cars, just a thermistor.

Dougflas on Wed July 03, 2013 5:28 PM

The only time I have ever heard that a variable orfice worked was for a mail delivery vehicle that went from mailbox to mailbox at very slow speeds.
I would also check the calibration of your thermometer with a glass of crushed ice.

Edited: Wed July 03, 2013 at 5:30 PM by Dougflas

bobinyelm on Wed July 03, 2013 6:15 PM

"What kind did I use?"

Interdynamics R-134a "Stop Leak and Detector," that says it's "recommended for Factory and R-134a Retrofits."

Their Part Number LDS 1, 4oz

fix_it on Wed July 03, 2013 8:37 PM

I'm pretty sure that is the "o-ring conditioner" type sealer. It only mentions fixing leaks in rubber parts. This is the least damaging of the two sealers. It shouldn't harden up inside your system, and can be flushed out. Now, the question is how long it will take to turn all your seals to mush.

As to the high side service port being located on the compressor, I think the 96-99 GM trucks had both ports on the compressor manifold. I wouldn't think it would be a problem.

bobinyelm on Thu July 04, 2013 11:48 AM

Thanks-
That's a relief!

I liberally coated all of the O-Rings with Nylog Blue as also recommended. Hopefully that will help preserve them (unless it's also a BAD thing).

Hard to know what's good, and what's bad these days!

fix_it on Thu July 04, 2013 12:57 PM

No, Nylog is not a bad thing. In fact, it comes highly recommended here.

I did not mean to scare you about the stop leak stuff, but I have heard plenty of horror stories from the "super seal" stuff. Like replacing every single component bad. From your vent temps you posted, it seems the conversion went well. The pusher fan I believe is a huge help.

iceman2555 on Fri July 05, 2013 10:29 AM

The location of the high side service port will not produce copious amounts of lubricant...will not flood you gauges....will not lock up the compressor.....however, it is possible to see slight gauge vibrations or movements. Noting serious, just that the needle may 'bounce' a bit. Nothing to be concerned with. This is merely the pulsation of the discharge side. Some produce this issue and others do not. The correct new replacement compressor for this vehicle does have service ports in the manifold. Not sure where this info was derived, but it is truly bogus. Sanden for many years utilized ports in the rear head of their units, Seltec/Zexel has also. Denso utilized a manifold on several vehicles that had the high and low side ports. GM did the same thing with the HT6 on some GMC trucks. Do not worry about this aspect.

A bit concerned for the choice of the 709 unit. The SD7H15 would have been a better choice and there is the correct unit as a replacement, the Seltec/Zexel model DKS15BH. Just a preference.

As others have stated, the variable orifice tube is not a favorite....as to the stop leak....'seal swellers' do not clog the system as to hardening agents. Not a fan....why not located the leak and repair it. Also, keep in mind the leak indicated by the loss of vacuum may not be from the system but from the manifold/hose assembly itself. The stop leak chosen should address an issue with leaking seals or orings. It appears that you are assuming that the leak is in the seals and not a mechanical leak. The system should be tested to locate the area of concern.
This is a substantial leak....insure it is repaired.

The use of the Nissan condenser? Was this merely a size/fitment issue...is it a high efficiency unit? If so, then the suggested undercharge maybe excessive and the result would be lose of performance and possible premature compressor failures. Increase to 90-100%. The condenser should be sufficient for cooling.

It is essential that the system be fully charged to insure lubricant migration for the compressor. Keep in mind, there is not 'set' recharge amount for a retro fit. Different charge rates have been suggested over a period of time...75...80...90....95 %. All derived from various sources....and often pressures were the guiding factor. The system should be charged as near OE spec's as possible to insure system performance and component longevity.

Good luck.

-------------------------
The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

94RX-7 on Fri July 05, 2013 12:07 PM

iceman2555 on Fri July 05, 2013 3:17 PM

Gonna need new glasses very soon...very damn soon.

Wonder if the unit was a HiEff unit or the standard serpentine type.

-------------------------
The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson