A/C issue on '98 Explorer

[scotts90ranger]

I know very little about the A/C system on these, I haven't had A/C for most of my driving career but the wife wants it since my current DD has working A/C

Anyway, '98 Explorer 5.0L Eddie Bauer if it makes any difference. The A/C compressor would cycle for like 2 seconds constantly when I got it, I got one of those silly DIY kits with the can and hose to top it off since I know R134A leaks since it's smaller than R12 was back in the day (I am an engineer... just been ignoring the system all these years). Anywho, I topped it off to the pressure it recommended based on the outside temperature, pressure went up when compressor was on but gauge went down and tripped the 20psi cutoff which turned the compressor off. Then I had the brilliant idea to relieve some of the vapor pressure in the system then top it back off with the can. That's when the compressor stopped coming on...

I think I'm going to be stuck going to a shop and giving them around $100 plus parts to get it going but figured I'd ask you guys first... I just hesitate to put that kinda $$ in a $600 rig... not against it, just not used to things I can't fix...

 

[adsm08]

AC is very easy, and relatively cheap to do at home, without those stupid cans. They really are a predatory product.

I have a set of manifold gauges that cost me $25 or so from HF, and a venturi vacuum pump that was about $20. Digital scale from ebay, don't remember exactly what I paid, and a 30lb can of 134a that cost me about $100. You pay almost $20 for a 21 oz can of AC Pro.

The only truly good way to charge a 134a system is to start from scratch. Vacuum it down, hook your gauges to a can, purge the yellow line, zero the scale, and open the low valve to start charging. Sometimes, like today, I have to heat the can to get the last bit in quicker.

 

[Craig0320]

Yep same here. Those quick can gauges are junk. I used my manifold gauges and never had a problem. Usually I just put the can somewhere on top of the engine while it is running to heat it up.

 

[adsm08]

Usually I just put the can somewhere on top of the engine while it is running to heat it up.

That works nice with the 1lb can. My 30 lb cylinder does not like to sit on top of most intakes nicely.

 

[kimcrwbr1]

You charge a system by weight not pressure a clogged expansion device is the most common fault. Clean the orifice and then do a pressure test with nitrogen overnight. If it holds pressure then vac it down at least two hours into a deep vac to remove all moisture and the add refrigerant with a scale. Start the engine and turn the a/c on as you add refrigerant the compressure should pull the refrigerant in until you add the proper amount by weight. Your goal is 20 degrees delta T. The air coming out the vents should be 20 degrees colder than the air going in under the dash.

 

[Denisefwd93]

Let's be realistic, almost no one's going to have nitrogen with two stage regulator, guages, vac pump, except people that are in HVAC. Maybe some automotive shops use it but I doubt that also.

Most people think they can fix anything after they can fix a few things it doesn't mean they should or could. That includes me lol

When you take apart an auto air conditioning system, and let's stay specific to Rangers because that's where we are. A new orifice costs about $4 don't even try to clean it you'll probably just damage the micro mesh screen,. And don't put it in backwards because it looks like it's backwards when it's forward.

Everybody's going to look for a easy way out. Virtually no one's going to weigh it in. Read gauges, temperature pressure charts for corresponding refrigerant pressure and temperature, or know about temperature difference.

if you're going to dump refrigerant into it and it's cooling or starting to cool and the compressor is going on and off less and less try to at least get it to the point where the line going into the accumulator is cold and sweating, if the accumulator is cold and sweating you "could" be overcharged. If the compressor is cold and sweating you are definitely overcharged, yes the compressor can get warm even hot when it's running.

Another also, everybody wants to add oil to their system even though they don't know what they need or how much they need, If It makes you happy get one of those little cans with 4oz of oil in it. It may help, probably won't do any harm.
The high pressure connection on the muffler or in the high pressure line was actually used by the factory to charge the system on a production line it uses a rubber type of poppet valve instead of a schrader valve (on the older lines) they have a great tendency to leak you may be able to turn it off and put on a new one, http://www.schraderinternational.com/_/media/Schrader/Files/Document%20Library%20PDFs/North%20America/AC%20Valve%20Manual_User%20Guide_10-21-13.pdf

(but you're probably better off just replacing the lines which are not very expensive but that means you're going to be working on a system that you think you can fix but you don't know if you can because you think you can fix anything because you fixed a few things. Lol)

Nitrogen.. cylinger pressure is 1000-2000. step down with reg to a "safe" pressure for auto air (under 200 pisg)

 

[4x4junkie]

You didn't release ALL of the pressure when you released it, did you? If you did, then there is a possibility the system could've have gotten air in it and will need to be vacuumed down (evacuated).

Like was said above though, A/C work is pretty straightforward, you just need the right tools, which as said there are inexpensive options available that do work well... Although I have found venturi-style vacuum pumps to be a little marginal, you need a rather good-sized shop compressor that can maintain 115 or more PSI during operation for such a pump to pull a good vacuum (this is much more than the 90PSI some claim to only need, something my nice 5HP Craftsman compressor barely can do, and only if I pull the little felt intake filter off it). A rotary-vane type vacuum pump will pull a more consistent vacuum, and is maybe $60 or so at Harbor Freight.



IMO, on a system that hasn't had a history of working while in your possession, it's best to just disassemble the whole thing and give everything a once-over. Replace the orifice tube, accumulator, flush out the evap and condenser w/solvent, dump any old oil out of the compressor (or replace both the compressor & condenser if you find significant debris and/or sludge in the system), replace all the o-rings (and hoses too if any look questionable or have an oily film on them), refill with new oil, reassemble, and then vacuum & charge with the specified amount of refrigerant. This way you'll know for sure there is the proper amount of oil in the system, and you'll have new fresh seals & o-rings.

IME, final results have been more consistent this way too... On a couple occasions just adding refrigerant from a can you buy at the store (adding just until the point the accumulator starts to take in liquid refrigerant), I've not been able to get the air temperature coming out of the vents much lower than 55°F or so, whereas starting with a clean slate I've had the final result be below 45° every time (sometimes less than 40° even).

I just hesitate to put that kinda $$ in a $600 rig... not against it, just not used to things I can't fix...

Why should that even matter?? A rig isn't worth some arbitrary value that you paid for it, a rig is worth whatever you feel it is worth to YOU. I assume it runs well and looks nice? If so, it's probably worth a heck of a lot more than $600... (it would be to me) The car is already in your possession... Use the extra $$$ you saved to make it 100%. I'd have no qualms putting ~$700 into that to have nice cold A/C (what it took to fix the A/C on my BII 10 years ago, no regrets either).

 

[adsm08]

Although I have found venturi-style vacuum pumps to be a little marginal, you need a rather good-sized shop compressor that can maintain 115 or more PSI during operation for such a pump to pull a good vacuum (this is much more than the 90PSI some claim to only need, something my nice 5HP Craftsman compressor barely can do, and only if I pull the little felt intake filter off it).

I should have mentioned that I have a rather large compressor that can keep up with the venturi type. If you don't have a large compressor the slightly more expensive electric pump is the better option.

Why should that even matter?? A rig isn't worth some arbitrary value that you paid for it, a rig is worth whatever you feel it is worth to YOU. I assume it runs well and looks nice? If so, it's probably worth a heck of a lot more than $600... (it would be to me) The car is already in your possession... Use the extra $$$ you saved to make it 100%. I'd have no qualms putting ~$700 into that to have nice cold A/C (what it took to fix the A/C on my BII 10 years ago, no regrets either).

This is something that has always puzzled me too. The other week I had a guy tell me he wasn't going to spend $25 on a sensor he needed to fix a check engine light because he only paid $300 for the car. Like, OK, you got it cheap, that means you probably need to fix some stuff, and since you didn't pay a lot for it you should probably have some money available to buy parts.

 

[scotts90ranger]

Just a slightly different mindset really... sure it's worth more than I paid and I know that the drivetrain (5.0L and good working 4R70W) are worth more than I paid... the main issue is I got married last August and just went on an Alaska cruise in June, credit card hasn't recovered from either yet... and I've been DDing a different V8 explorer at 16mpg instead of the Geo Tracker (blew a head gasket last July) that got 26mpg 60 miles a day...

Looks like even without coupons at HFT the manifold and vacuum unit are about $75, well within reason. I'll do some more research on how much refrigerant it'll take and how much my F350 will take while I'm getting stuff and just jump in. My compressor isn't big but it isn't small either so I'm sure I can make due with the venturi version

Thanks for the input, I didn't figure it was hard just haven't looked into it.

 

[Denisefwd93]

Not to hurt your feelings, but I'd suggest you just take it to a shop, you really don't know what you're doing.

This is a confused statement:. " R134A leaks since it's smaller than R12 was back in the day (I am an engineer..."
Uh...

Refrigeration engineering has developed seals, hoses, lubricants, and metering devices specifically for R134a. it has much smaller molecules, it may leak where R12 did not on very old systems that did not have barrier hose.

In you're very first post you were putting in refrigerant and then letting it out to "relieve pressure" that's a clear indication that you're very confused on how the systems work.

 

[scotts90ranger]

Very true, I just hadn't looked into it, and I might still take it to a shop. I'm sure the system needs to be purged and the orifice changed. I knew there was a restriction in the system as the sensors were seeing too high of a differential pressure in the system, the pressure on the low side with the can gauge was high but when the pump kicked on it went down to 20psi and turned the pump off after about 2 seconds. I was just running out of ideas and experimented... I know the change from high to low pressure is what causes the cooling. At that point I knew parts needed changed, just hadn't researched it yet.

Anyway, research and decisions are ahead

 

[Curious Hound]

The low side pressure is supposed to drop when the compressor turns on. The pressure readings that matter the most are with the compressor running and doing its job.

This message composed solely of recycled electrons. Go green!

 

[scotts90ranger]

I understand that and was the initial problem, I'd get the pressure up with the compressor off then it would drop below 20 psi where the low side pressure sensor turns the compressor off, so I tried to relieve some vapor pressure then re top off with refrigerant (did I miss that detail before? I didn't just mean that I was relieving pressure...) which backfired now the compressor won't turn on...

My first post in this might have involved whisky, I should probably not post detailed questions after a couple tall drinks...

 

[Denisefwd93]

Refrigerant is not "topped" LOL me thinks it's drinks you be thinking.
Anyways.. to get anywhere with this.. assuming you are looking for help.

I may not be a the sharpest tack in the box.. but I know a little about hvac.

Let's start with what you have.
98, V8 explorer. Not new.. but not really ancient.
Ford designed AC,
You added R134 and it starting working but somehow without knowledge you decided the low was too low and the high was too high and released it.

Now, it doesn't run at all. most likely you don't have enough R134A to even close the low pressure switch. (also the compressor cycling switch)

I'm assuming the ac on the the 98Exp is about the same as the rangers and most fords of that vintage. (it may not be)

To help; Need to know outdoor temp. condition of Rad fan, (do you have good air flow? and can you hear/feel the fan moving air when it's hot out?)

next time you try to charge.. at least try for the low pressures on a chart like this. (high pressure is usually not worth checking and you run the risk of having a high side port leaking afterwards) there is a high pressure cutout switch on the HP hose near the muffler, and HP relief on the compressor. more experienced just check the HP out of habit.

the compressor will and should go on and off.. less and less as the system starts to "perk" .. You need 1000 -1200 rpm and good air flow to even guess if it's starting to cool..

there is no '"SET" temperature.. the cold will slowly get colder as the cab gets colder. air coming out should be 15-20 colder then the air in the cab.

The condenser is hard to check because of the radiator. but it would be 15-20 degrees hotter then the air going into the front grille.

I would suggest NOT opening the system yet. it had a little pressure so it would not be contaminated and most likely just needs a proper charge and leak checking.

 

[4x4junkie]

the pressure on the low side with the can gauge was high but when the pump kicked on it went down to 20psi and turned the pump off after about 2 seconds. I was just running out of ideas and experimented... I know the change from high to low pressure is what causes the cooling. At that point I knew parts needed changed, just hadn't researched it yet.

Sounds like it is working exactly as it is supposed to. There's simply not enough refrigerant in there.
When the compressor turns on, what little refrigerant is in there all gets pumped over to the high side, leaving nothing available in the low side to keep the pressure switch tripped. If you keep putting refrigerant in there, eventually the compressor will stop cycling off after there's enough in there that the low-side pressure doesn't drop down so low (however there are some circumstances the cycling switch will still cycle the compressor even with a fully-charged system... When it's very cool outside for example).

Here are two resources which I found invaluable when I started researching A/C repairs for mine:
https://www.amazon.com/Haynes-Techbook-Automotive-Heating-Conditioning/dp/1563929139?tag=959media-20
www.autoacforum.com


Just watch the gauge on your compressor when you run the vacuum pump. If it begins to drop below 115PSI while it's running, then it's not big enough (also if it kicks off, but the switch doesn't kick it back on before dropping to 115 PSI, isn't good either).