strange cooling

[grumpy old man]

So I picked up a variable orifice for a Crown Vic Police cruiser at the Ford parts counter. This unit did come of a totaled low mileage police cruiser and because they spend considerable time idling they have the variable orifice. I clamped the pressure hose and manually triggered the clutch to suck the evaporator dry. I was showing less than 5 psi on the low side and about 140 on the high side, hoses were clamped and the pressures were not equalizing so theoretically there should have been no pressure in the evaporator. So I figured it should be safe to disconnect the high pressure hose. I worked the tool in to release the spring, the hose blew and at least a pound of refrigerant and a whole lot of oil blew back out of the evaporator. I still had the 140 pounds showing on the high side gauge so there must be a blockage in there somewhere. I plan to pull everything out and flush it thoroughly to see what I find. Maybe by this time tomorrow I might know something.

[bohica2xo]

Sounds like fun. I try not to work on pressurized systems myself.

Did you pull that evaporator out of a wreck yourself? Junkyards are sometimes less than truthful...

Sounds like it may have had some sealer in the system. A new evaporator core will fix that.

[grumpy old man]

Working on hot systems is not an activity I indulge in often but for the orifice I used to clamp hoses off, pop the connection apart and slide in a new orifice. Did not do many but those spring connections come apart and go back together so easy and it saved so much time that what the heck. I have honestly never seen a plugged evaporator but I got out of the business around 2000 and I do not remember sealers back then. There must have been about a hundred pounds difference between the inlet and outlet on the evaporator. It does pass air right now but you can feel restriction in the thing, probably blew out some stuff when I broke that connection. I put the new evaporator in today but am still waiting for the new accumulator.

I salvaged the unit myself out of a low mileage 98 cruiser just before it went to the crusher. However it did not go into where it was intended and it wound up on an upper shelf where it sat for close to 20 years with the lines open. No telling what might have set up residence in there.

Hopefully when I get the new accumulator in and get it charged it will work. I do not know what I did to anger the A/C gods but in the last 8 months I have had to replace the entire system in a condo rental, the upstairs condenser and evaporator on my house and now the downstairs unit is failing. The exclamation point is this unit in the Pontiac. Is it possible that it is just rejecting the transplant out of a Ford?

While I had it apart I took several pictures which I will post If I can figure out how. I think it is a real clean installation, I certainly have enough hours in it.

[grumpy old man]

So I now have a new evaporator, orifice and accumulator. It will frost the accumulator which it never did before. I have the gauges duct taped to the windshield and the pressures are strange to say the least. At surface street speeds, 30 to 45, it is cycling off at 12 psi and on at 42, high side at 150 compressor running drops down to 140 clutch off nozzle temp at 44 air on recirculate. 85 degree day somewhat humid. As soon as you stop at a traffic light the high side will creep up to over 250 in less than a minute. at freeway speed the low side will suck down to about 3 psi the high side is down around 120 nozzle at 50+ and the clutch does not cycle. as soon as vehicle speed drops down under 40 the clutch cycles and the pressures go back to the 12/42 and 150.

The high pressures at idle says to me that the electric fan is not putting out the 3000 cfm advertised however if you put it in neutral and bring the engine speed up it does not change much even with the solid 7 blade fan which does pull a lot of air.

I have no explanation for the pressures at freeway speeds.

I am at a loss, what do you think?

[grumpy old man]

OK so I figured out the clutch issue at freeway speeds. The air is spinning the electric fan and it is generating enough current to back feed and keep the clutch engaged. Hows that for weird? So bottom line is that I need to isolate the fan on its own relay so it can't back feed.

The other issue is that it seems that the stacked condensers don't work, at least as I have them connected rear to front. The refrigerant going through the front condenser last seems to be over cooling it if that is actually possible. So is there somewhere out there a parallel tube condenser in the 26"W X 18-20" H range. I have not been able to find one which is why I stacked them in the first place. The other option would be to make up some fittings that will run the coolant through the condensers at the same time, but the parallel tube would be the best answer as I am sure that the air restriction would be less.

[71403]

Those dimensions are pretty close to a stock Crown Vic condenser. The later Crown Vic is factory PF but has trans fluid cooler integrated below the condenser. Another close in size is early 90's GM full size trucks. A lot of original tube/fin condensers are now supplied by the aftermarket in PF.

[grumpy old man]

What year range of crown vic is the factory PF, I can ignore the trans cooler if I can make it fit. Let me rephrase that, I can make it fit but with how much surgery? For most of the installation I had the front sheet metal off doing the rust thing (the joys of an eastern car). I would rather not do that again as the paint on all the front end sheet metal is fresh.

So the operative question is where can I find exact measurements on the condenser?

[71403]

06-11 is factory PF. Did a '03 CV last week the failed condenser was serpentine but the aftermarket replacement was PF.

Site sponsor might be able to get you better measurements but I have is 27" x 19". Not sure if that is overall or core. If your taxi shops are anything like ours they will have a bunch of plugged or leaking ones in the scrap pile.

[bohica2xo]

I have two condensers I like to use for swaps & retrofits on pre-70 cars with top to bottom flow radiators. The aspect ratio of the older radiator can be hard to match up with.

1) The condenser from a 2003 to 2007 Cadillac CTS

Core size is 17 inchs high, 22 inches wide. This is the airflow area
Overall size. The core height of 17 is all of the height, but the 4 mounting tabs extend 1.5 inches from both the top & bottom of the core. The overall width is 26 inches including the dryer. Most new cars include a dryer mounted on the condenser, go ahead & use your larger receiver dryer as well.

2) The condenser from a 2006 to 2012 Dodge Charger (and lots of other models too)
This condenser includes a great transmission cooler, use it if you need one.
Core size is 18 inches high, 23.5 inches wide. This is the airflow area.
Overall size. The height remains at 18 inches with no mounting tabs. Width is 28 inches, with mounting tabs on each end, a dryer, and fitting bosses.

Both of them have plenty of capacity. Please do not buy a used parallel flow condenser, they are the primary filter in the system. New units for either of the above condensers are around $100

You will however get to make a trip to your favorite junkyard. Both condensers use unique fittings and you will need donor car parts to make hoses from. The transmission cooler on the Dodge part uses a push to connect fitting as well so you need to scrounge 4 fittings for the Dodge part.

Hope that helps

B

[grumpy old man]

OK I have a NEW parallel tube condenser added to the new evaporator. I spent the last week modifying the radiator header, trying desperately to protect the new paint from the mig welder splatter and the grinder, so the evaporator is now behind the header about 3/4 inch in front of the radiator. I redid the radiator mounts and the fan shroud to get it tighter around the fan. The AC works fine now as long as I am moving. I had to go down town today so I thought I would give it a try. Weather running close to 100 with relatively high humidity and as long as I could keep going at least 40 the AC and engine temp were fine. As soon as the traffic stopped the nozzle and engine temp would instantly start climbing. I believe that I am down to just getting more air flow, and possibly more coolant flow.

I need to find a smaller pulley for the water pump to spin the fan up because in stop and go traffic the engine temp was reaching critical. I turned the AC off and by putting the car into neutral and running the engine up to around 1200 the temp would start to come down and on the freeway it would only take a couple of miles at 60+ to get the temp gauge from around 350 down to 180 and the nozzle temp down to around 40 so I think that if I get the fan spinning faster it will solve the engine temp issue. The existing pulley is 7 3/4 inches which is pretty big in comparison to every other vehicle I have. This thing is geared so high that the engine is barely off of idle in city traffic and under 3000 at freeway speeds so a smaller water pump pulley will not over speed anything, the problem is finding one that will work. No one makes pulleys for early Pontiacs so I might need to spend an afternoon at Pick a part. 100 degree weather will find the shortcomings in any cooling system.

I do not believe that the electric fan is delivering the advertised 3000 cfm. So I am on the search for the most powerful 16 inch pusher fan available, or possibly two smaller fans to cover the entire 24 inch width, maybe staggering them so every tube is covered by a fan blade. I know that my old 500sl has two fans on it that move a LOT of air.