A/C relay questions

[harpon]

This isn't about a Festiva, but I'm trying to get the a/c running on a 95 Escort wagon- I got some Freon recharge put in a few weeks ago and the system seems to be holding that well- so I think that's fine-

The problem I first thought was a relay- there are two A/C relays back on the firewall-

The original behavior seemed to be a clicking in one of them, so I got a new replacement-
at that point I noticed the other relay was actually clicking first, then the new black one on the right, then both click simultaneously-
it seems the ac clutch may be engaging for a brief moment, but turning off again by the time they both click the second time simulraneously-

Today I got some used relays at the junk yard- no matter what combo of the two or three of each side I try, the result is the same- click left, click right - click both off right after- and no cooling- today I noticed a line behind the firewall is cooled quite a bit- but not getting inside- the other ac lines feel maybe just a little cool

I've jumped a couple of wires on the left relay socket, and the clutch seems to engage and STAY ON- no reaction from the black right relay then- and NO COOLING inside-

so now I've decided its probably not the relays but some other short somewhere that clicks them both off?
The left socket jumped seems to engage the clutch - what do you think the right relay does?

I had trouble corroborating part numbers and descriptions trying to order relays- the left didn't seem to even be listed- but 5 of about 6 cars at the junkyard had them intact, and I got out of there with three relays, some pal fuses for the fussyble Festy links and some retro fitings for the Festy system for less than $5 excluding the admission- VERY HOT DAY!

since they act the same with every combo- I think the problem must be something else- the dash board functions seem OK and the AC light comes on- with the relay set normal- the motor does not seem to react to turning on the ac button.

Anybody worked much with this who may have an idea?
- I don't even know where to start tracking down a short- Both under hood ac fuses OK as well.

Only the middle PAL cartridge fuse fits the Festy fusible box, the outer two don't have enough slot in the middle to push down far enough- I may try to enlarge the slot- nothing to lose. Don't know much about the ac systems though and so far frustrated.

[tooldude]

Are you sure the system is charged with the right amount of Freon so it's not being cut off by a pressure switch?

[Movin]

Did you evacuate and recharge to get the right amount in? The amount should be on a sticker somewhere. If you did not get the system evacuated and charged you have to have the system running to pull in the last half of the charge. Or you can cook the can until it is empty. The cans oz should add up to the sticker amount if there was only gas , no liquid, left in the system.

The low side switch is not seeing enough pressure to tell the relay to keep the clutch engaged for 20 seconds or so then off for 5 seconds or so at idle.

[harpon]

I used a can with a guage in the hose- so according to that there is enough pressure. A little into the first warning zone really. I was surprised there was near full pressure when I added a little more, because I thought at first it just needed charging. It is 134 Freon originally- no refit on the 95 escort. I first put a bit more into my 96 Aspire- never had any trouble with the ac and very cold now.

If the relay or harness was NOT engaging the clutch correctly then, could that have given me a false reading then?

[Movin]

Some of these had cycling switches that had short life problems. With the car idling and the ac turned on you can jump the two terminals and see if the relay engages the clutch. If it does you need a new one.

http://www.oreillyauto.com/site/c/detail/MRY0/36494/01957.oap?year=1995&make=Ford&model=Escort&vi=1119327&ck=Search_01957_1119327_3113&pt=01957&ppt=C0039

[harpon]

Hey thanks for the info Movin-
Double post- sorry

[harpon]

Hey thanks for the info Movin-

I've found the part and it's not expensive and located it on the car-

I've yet to jump the connections- you mean on the cycling switch, right?

I see the part has internal threads on the other end- does it thread directly into the line, and does the system have to be purged to install it?
Will I have to put in all new Freon if I put one on?

http://www.ebay.com/itm/Ford-Motorcraft-YH552-OEM-AC-Compressor-Clutch-Cycle-Switch-F3AZ-19E561-A-/121422647336?fits=Year%3A1995%7CModel%3AEscort&hash=item1c455a9028&vxp=mtr

(not the cheapest one there but the best picture)

- my Haynes manual has no info at all on the a/c system.

[Movin]

You will lose no freon, it is like a tire valve. A quick puff is all. No liquid loss. Jump the connection in the plug. If it tests bad put a little AC oil or vasoline on the oring before installing the new part at 5 inch pounds, or grip and turn it like a screw driver in your hands, like you mean it lol, that is about 5 in. lbs.

[harpon]

Hey thanks- maybe sort it out some more this weekend.

[harpon]

So- still messing with this and still no luck.

The part that first came up on the ebay search turned out to NOT be the right clutch pressure cut off switch- I had to pull the one off to confirm that it was not the right part- mine was rounded with FOUR connectors, not flat with two- Luckily I got the order canceklled on Sunday before the shipment went out.

when I pulled the part off, the valve didn't want to close again, and so I lost a lot of Freon, but I still had enough in my large can to get it up to pressure when the right switch got here today.

It's looking more like it might be the compressor itself I guess, or maybe the connection to it, or some other short or grounding issue.

With the new part in- only $10 luckily- it all repeated the pattern again. Nothing at all was happening again until I jumped wires at the connector which apparently engages the clutch. Yet it doesn't seem to produce cold anywhere. After the clutch is jumped once the relays then do exactly as before. One clicks , then the other, the clutch seems to engage for a second, then both click at the same time off, and repeating this pattern every 10 seconds or so.

Doesn't look I'm gonna get it going. I can get a rebuilt compressor for about $100, and I'd have to get it installed then. What do you think my chances would be of it coking up then?

I'm probably going to try to sell the car without the repair, but if I ever used it as a daily driver I guess it may cost about $200 or so to repair- and a good thing to have in Florida summers.

Here it is beside the Festiva. Gotta get some pictures of it alone- The last ones I took were before replacing the rear bumper- HARD to find, except at Pick a Part, and not many of this era there now either.

[tooldude]

If I am not mistaken about any of this - You can only troubleshoot the AC accurately if you can check both high side and low side pressures with the compressor running. If the system has absolutely no problem and only needs freon, then you could probably get it operating by getting near the full charge, then carefully & *very slowly* adding freon while watching a thermometer in a vent checking only one side's pressure (while running). The engine needs to be running fast and a large airflow (fan) needs to be in front of the condenser. This is not recommended and risky to overcharge, getting liquid in the compressor and ruining it. Plus, the proper oil/charge ratio is not established. You cannot measure the amount of freon in a system by reading static non-running (nor running) pressure as a small amount of freon will create a vapor pressure equal to full charge pressure and varies by temperature (the same pressure will be in a small can as in a huge can). These kind of risky attempts are only possible to work at all in old systems that held several pounds of freon because of the extra reserve capacity. That said, I believe your system does not have enough freon, if everything else is good. Exactly how are you checking pressure and which side? I hope you know not to hook a can to the high pressure side and have it blow up on you.

[harpon]

no- I've only added on the low side. Does it balance the pressure otherwise? How long would the clutch on the compressor have to be engaged. Can I read it on the high side otherwise?

[tooldude]

Pressure equalizes throughout the system with the compressor off, as long as there is no blockage anywhere because it is a continuous loop of tubing. The static (non-running) pressures will be the same on high and low sides. The "sides" exist on either side of a component with a small restrictive orifice when the compressor is running. This causes buildup of pressure from the pumping side of the compressor and low pressure on the suction side of the compressor. The proper control of low pressure allows the refrigerant to boil off at the needed temperature and the proper volume of liquid refrigerant through the orifice allows for the needed amount of heat transfer in BTU's.

[tooldude]

Rule#1: This is to the best of my knowledge, but is not recommended. Absolutely Do Not do the following procedure unless you are willing to risk damaging the A/C, determined, doing-it-anyway, etc.! If the system begins to cool, you will be tempted to keep adding freon to get it colder. That's risky because a malfunctioning, fully charged (or overcharged) system may be only partially cooling and will not improve with more freon. It can only be accurately tested with proper charge, which *cannot be determined by pressure*, only by weight/volume. (Unless the A/C was previously working and only the freon leaked out - this is a good place to stop). An A/C manifold with high & low pressure gauges on it should be used, high-side pressure performance of the compressor should be watched. Your gauge can show the approximate low side pressure, however, but only if it can be cut off from any can pressure - outboard of the valve. You can use it if you did not empty the can and then let air get into it, or can isolate the gauge. You should purge air from the hose before you connect it, by slightly opening the can valve before connecting. It will purge in a second or less. Otherwise you will be adding air & moisture. The following MAY show if the A/C can cool: Connect your gauge to the system. If your car has been sitting so that everything is at/near ambient temperature you will see the static vapor pressure for R134a at that temperature - approximately: 71 PSI@70*F; 87 PSI@80*F; 104 PSI@90*F. If you don't see pressure that high, the system has a serious leak and there is not enough vapor to make normal pressure (since you have just added freon and now it has leaked out - this is a good place to stop). If there is pressure, turn on the A/C, start the car, speed the engine. Watch the gauge from the start - may need a helper. The static pressure should start dropping and operate at the proper low side pressure for your system. If it rapidly drops very low, say below 15 PSI, BEFORE the compressor is cut off, the system MAY be low on freon. Do not just arbitrarily add freon. The risky part: Note the cutout pressure and slowly add freon to see if that cutout pressure is rising slightly because of a low charge. If it does, the compressor should begin to stay on longer. If the compressor starts making noises, the pressure may be getting too high or liquid is getting in (now you must stop). You need to know the specs for your system. Depending on type, normal low side pressure range could be approximately 16-45 PSI or 24-50 PSI for example, and is affected by total charge, compressor speed, high-side pressure and airflow over the condenser (see my other post), & ambient temperature. If low-side pressure drops very little or cannot even reach the middle of the range for your system, maybe 30 PSI, the system probably needs servicing. This is where you need to see the high-side pressure for too little pressure or overcharge & too much pressure. The most cooling occurs when the pressure inside the evaporator (not at the gauge fitting) drops from the higher static pressure and is around 26-28 PSI and then R134a evaporates near 32*F without icing up the coils. Around 45 PSI it evaporates at 50*F so there should be slight cooling. Be aware that improper service will take a percentage of toll on performance and/or longevity, even if there is cooling.

[Movin]

Completely agree. There are generally 4 different ways AC can be installed in a car. One is from the car maker factory, Ford. Another is it came with another manufacturers supplied components, partly. Mazda for instance. Next would be Dealer installed. Typically from Ford but not with the same components. Lastly Aftermarket installs as well. Parts and quantity of freon can vary widely. If you do not have a capacity sticker go to a parts store and have them look it up. Generally you can purchase different cans to arrive at the correct amount or close enough. But to use this accurately the system has to be held in a vacuum for 20 minutes or so.