Engine Size: 5.2
Refrigerant Type: R-134a
Ambient Temp: 85
Pressure Low: 65
Pressure High: 500
Hello all. My name is Mike, and this is my first post here. I've seen some really great puzzle-working from the members on this site, and it has helped me before on other A/C jobs. But now I have one I can't figure out.
A customer brought in his Dodge van with a minimal-to-no cooling complaint. My experienced and trusted gauges read the pressures recorded above. I took a few steps back. My first thoughts were a Criminally Negligent overcharge, or air in the system, but the van's owner and the dust on the valve caps say that the system has not been touched any time in the recent past. Next on my list is an ineffective condenser. However, it appears to be in working order, and the fins appear to be clear when viewed from the front. The van uses an engine-driven fan which works as it should, and also does not have any engine cooling issues that would otherwise indicate an airflow problem. As far as I know, a stuck TXV would create low low side pressures and high high side, as would a blockage in the receiver/drier, but not to this extent.
The van does have dual-air, but no combination of both or different systems being turned on has any effect on pressures or behavior.
The compressor is making nasty noises consistent with ~600 pounds loading each of those poor little ball-jointed Sanden connecting rods every tine it spins over. I'll most likely replace it when I figure this out and just retire the veteran unit after countless courageous trips to the high pressure cutout switch and back.
Here's the kicker: Spraying the condenser with water will immediately drop the pressures drastically, until they are in the range of 200 high/36 low. The system proceeds to blow nice cold air. I know this trick usually indicates an airflow problem, but where could the air possibly be blocked? Again, the mechanical fan and clutch are working normally, and the engine is running at the correct temperature. There is no electric pusher fan, and the van has had no ft end damage. Am I looking at a condenser or radiator that's just been plugged with bugs and rocks? Are there any known issues you all know of that could affect this van's A/C?
Thanks for the help.
I bet that the condensor is plugged internally. Either from a past compressor, the curant one or the dryer is coming apart.
I'd suck it out and back flush the condensor just to see what comes out. If it's got metal or dessicant in it then a major is your only option.
Yeah, that's kinda what I thought. The overall design and construction of the condenser looks an awful lot like some I've seen on late-model Hondas, which have tiny little internal passages. What could have clogged them, I don't know. Also, the water spray did seem more effective on certain areas of the condenser: the top left in particular.
Any other ideas before I tear it apart and replace the condenser (and compressor...)?
The water test is going to be more effective at the top of the condenser as this is where the hottest gas is entering. You can try temp probing different areas of the condenser while operating the system; cooler spots could indicate a clog. Dust can accumulate quickly and eliminate evidence of recent work. I would test for sealer and or air in the system.
The OE fan (clutch?) could be very tired. Still producing enough air flow where engine overheat is not an issue, but no where near enough flow to adequately remove the heat from the condenser. Put a light in the fan area and see how clear the air path through the condenser and radiator really is. It may just need a real good external cleaning.
Overcharging will fill the bottom part of the condenser with liquid and render it ineffective. I agree one trip on a dirt road would cover everything with dust.
In a confusing case like this it is best to step back and start from scratch; assume nothing.
I think I am dealing with a combination of problems here. Consistent with what you guys are saying, and my hunch, and despite "not having any A/C work done", it does seem to be overcharged. I think I'll recover the system, pull the condenser and inspect it thoroughly inside and out, pull the radiator and make sure it's clear (probably replace--it is starting to seep anyways), and replace the compressor as a preventative measure. I'm sure it can't last much longer. I'll also use a new receiver/drier, of course. Also, though the fan clutch still has plenty of viscous drag to be considered good, I don't know if it's locking up or not. Probably throw a new one on there as well.
Does this sound like a good course of action?
It is always best never to assume when working of a vehicle that the true history is not known. As stated, go back to the basics..know for sure what you are actually dealing with. The first and most important tool of diagnosis of a 'non-functioning' AC system is to know how much refrigerant is in the system. Evac and recharge using the correct equipment..no cans...use a machine to insure that the system is properly recharged.
Determine what pressures one is working with...where is the service port (high side)? Before the condenser and with these pressures....one can be assured that the condenser is restricted. If the port is on the liquid side of the condenser, then one is probably encountering a loss of cooling efficiency...esp with the drop in pressures/temperatures when additional heat transfer (water) is applied. Considering the age of the vehicle and the possible mileage.....look at the fan clutch very closely. Simply because there is not an engine overheating problem does not mean that sufficient air is being drawn across the condenser for adequate cooling. The radiator is 'seeping'...this needs to be addressed....this condition adds additional cooling requirements for the system.
This vehicle utilizes a scroll type compressor and these units are known for producing tremendous amounts of debris when they fail....or are in the process of failing. Be aware of this when attempting to service the system. Also, removing and inspecting a condenser...not sure exactly what one would expect to see with reference to a restricted condenser.....could possibly fill the condenser with liquid flush....allow to remain stationary for 10-15 minutes and then 'blow thru' the system in a reverse flow pattern to determine possible debris encapsulated in the condenser inlet side. Introduce air/other gas purge at the outlet side of the condenser and reverse flush the unit. If debris is evident...a compressor change....possible hose assemblies....complete system cleaning to remove any residual debris from the system. This includes a complete service of the rear unit also. Leave any debris in the system and one is sure to be 'doin' it again'.
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HECAT-yes, a complete flush of disassembled components will of course be on the list.
I got the whole thing torn apart today, and for starters, I'm reasonably certain that there was too much refrigerant in the system. The high side port is in the high pressure gas line between comp discharge and cond. inlet. Sure enough, I found a cheap replacement condenser in place of what I expected would have been OE. In fact, the radiator, as well as quite a few front end parts in general had been replaced, suggesting a ft end hit. I went ahead and got a new fan clutch (not a cheapie-I know better from experience), so that's not a variable anymore.
Iceman, you called it on the compressor. I was unaware that Sanden made scroll compressors. I saw the Sanden label, and figured it was a standard 5-piston design like the one that was on a very similar 1996 Dodge truck I worked on a while back. I have seen the impressive aftermath of a catastrophic failure of a scroll compressor (hence the earlier reference to a Honda CRV system I completely rebuilt in May), and I'm really glad I caught this one in time. There is no visible metal flake, debris, or crud in the system, and the little bit of oil I could drain out of some of the lines was light-beer colored. So I think I dodged the bullet there. I still don't know what's wrong with the condenser, or why it would suddenly plug up, and I can't see around the internal fittings to examine the inside of the tubes, but I'm going to change it anyways. I had the local A/C parts store order me an AC Delco unit, which is described as OE-or-better quality. Have you all had good or bad experiences regarding the quality of AC Delco condensers? The old one--exactly the same as local cheapie--is likely chinese, there's no way (or need...) I can convince my customer to shell out for a stealership version, and a Visteon will take a week to get here.
Thanks for your continued input.
Just had another thought-
What does dessicant look like when the bag bursts and it's roaming around the system? Is it white, or clear, or colored, or does it vary? The R/D on this van has a Mopar tag on it. Would it be granular, or more like little clumps of gel?
I am glad to hear you have seen and have had some experience with the aftermath of scroll failures.
My opinion regarding the condenser(s): I think we all wondered how you were going to inspect internal condition. Even with a borescope, I can only see into the inlet chamber to the first set of crossing tubes. Offshore (aka cheap, chinese, etc.) manufacturing is very much the standard today. There is really no way to know if the brand name you can get, the one you can wait a week for, or the dealers version; are not from the same or similar offshore factory. The parts guys usually cannot comment or offer advice as to which one is better other than it "must be this one", because of its cost. Since I consider the "offshore" issue to be the norm (basically a non issue); I would buy one from AMA for the simple reason that they seek and inspect these items for the highest quality, and use them in the customer vehicles they service in the Phoenix area. Since they provide this forum (to get beat up if they sold crap) and have a desert proving ground for the products they sell; this is where I gain some comfort over someone just saying or describing it as "OE or better".
The desiccant can be white beads, granular, and sometimes similar to clay; so I think all your descriptions were accurate.
Was a bit curious about showing 500 psi on the high side, either the HPCO switch is bad or has been bypassed. 430 psi is the normal cutoff.
I was also thinking that. The gauge port is before the condenser, if the HPCO switch or sensor is after the condenser and wasn't cutting out (because the pressure is lower there), that would be evidence of a blockage in the condenser not just an overcharge or poor airflow.
Lemme tell you, it spooked me when I saw my high side gauge wrap all the way around...
The HPCO switch is located about 1.5" away from the high side port (in the discharge line), so maybe it's set pressure is higher than if the system were designed with it in the liquid line. The pressure hung right around 450 psi, then crept up slowly to about 490-495, then the HPCO opened. Pressure dropped to around 380 psi, then the HPCO closed, and the pressure quickly came back to ~450, and this cycle repeated.
Given that the switch is in the discharge line, does this sound normal? Mebbe I should replace it?
Just checked the AMA site, and unfortunately, there is no condenser offered for this van.
Edited: Wed September 23, 2009 at 11:01 AM by Gearhead
The HPCO switch is fine. Manufacturing tolerances, gauge tolerance etc can stack up & give a 60 psi offset. As long as it works you should be ok.
Looks like the low bidder body shop strikes again. The "seeping" radiator may not have been new when it went in the vehicle, same for the condensor.
Fullsize vans tend to rack up a lot of miles, so this repair could be a year old - and look ten years old.
Good job on your part, replacing everything in the heat exchanger stack / air path that needs it. I wish more techs paid this kind of attention to detail.
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