Big T
Well-Known Member
Bought the '99 in January and had no need for AC until now. Well the AC pumps out heat. I put one can of refrigerant in the system and no change. I guess I'm better at engines. Where do I start to trouble shoot this?
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AC Not Working
- Thread starter Big T
- Start date
Acesneights1
New Member
Did you even put guages on it ? Is the compressor clutch engaging ?
Big T
Well-Known Member
The can of refrigerant has a gauge on it. My son suggested getting a gauge for this from the shop. I have no idea if the compressor clutch is engaging. I don't hear anything engaging. How would I know? Again, this is not my area of knowledge.
:iagree: Plus this is a good place to ask for help.
If the compressor runs check that the silver can by the firewall, accumulator, is getting cold. If the can is not getting cold with the compressor running you have a big problem. (Like low side switch bad, low freon and low oil. Possible overcharge too.)
If the can is getting cold:
Cycle the heat and cold settings to make sure the heat mode door is working - engine off and listen for a thunk or door moving when you change the settings.
In any case these systems require a correct charge by weight. I recommend you have a shop recover the system and recharge it by weight. You can do repairs between the recovery and recharge. I recommend a VOV for your climate also explained in the posts below.
Good long post with lost of info here:
http://www.thetruckstop.us/forum/showthread.php?t=21925
Edit:
Clutch would click and start spinning with the AC button or setting. 1 can of freon will have the clutch start clicking and running on an empty system unless it leaked out from a blown line. The cycling switch could be bad and prevent it from coming on, common issue when charging a empty system. Should be the device on the driver's side top of engine on the 99. Your 95 has a different looking round pancake on the passenger side. Looks like this:
I can't recommend a proper evac (Vacuum), leak test, and recharge strongly enough for these systems.
If the compressor runs check that the silver can by the firewall, accumulator, is getting cold. If the can is not getting cold with the compressor running you have a big problem. (Like low side switch bad, low freon and low oil. Possible overcharge too.)
If the can is getting cold:
Cycle the heat and cold settings to make sure the heat mode door is working - engine off and listen for a thunk or door moving when you change the settings.
In any case these systems require a correct charge by weight. I recommend you have a shop recover the system and recharge it by weight. You can do repairs between the recovery and recharge. I recommend a VOV for your climate also explained in the posts below.
Good long post with lost of info here:
http://www.thetruckstop.us/forum/showthread.php?t=21925
Edit:
Clutch would click and start spinning with the AC button or setting. 1 can of freon will have the clutch start clicking and running on an empty system unless it leaked out from a blown line. The cycling switch could be bad and prevent it from coming on, common issue when charging a empty system. Should be the device on the driver's side top of engine on the 99. Your 95 has a different looking round pancake on the passenger side. Looks like this:
I can't recommend a proper evac (Vacuum), leak test, and recharge strongly enough for these systems.
Big T
Well-Known Member
With the engine off, I do not hear any flaps closing.
I checked the #12 fuse for heat/AC blower and that is fine.
With the engine running, I do not hear the compressor kick on. Normally, one would expect a slight drop in engine rpm.
I checked the cannister at the firewall and it's like ambient temp. Same temp as the intake side of the ATT turbo after running at idle for a minute.
I checked the #12 fuse for heat/AC blower and that is fine.
With the engine running, I do not hear the compressor kick on. Normally, one would expect a slight drop in engine rpm.
I checked the cannister at the firewall and it's like ambient temp. Same temp as the intake side of the ATT turbo after running at idle for a minute.
Acesneights1
New Member
If the compressor is not kicking on you would be unable to charge the system. I mean some would go in to the equal pressure of the can you are charging from but if the compressor is not running it will not "sucks" the refrigerant into the system. Put guages on and see if any charge at all is in the system and then if there is Jump the cycle/hi press switch at the drier with a paper clip and see if the compressor engages. Report finds back.
Big T
Well-Known Member
I'm checking this board during breaks from sanding wood windows on the house, so bear with me.
Exactly what gauges do I need and where do I put them on. I will have to buy these gauges. PepBoys? AZ? Kragen? Napa?
drier? Where is it?
Acesneights1
New Member
Don't have a pic but it's the big silver can looking doha by the firewally and should be cold when ac is working properly. Guages can be bought anywhere. Probably even Harbor Frieght although myself I use good ones(Robinair). I actually never cared for the Snap On ones. I found they didn't last as long.
Big T
Well-Known Member
OK checked it with my son (he's doing the optic sensor change on the '95).
Jumped the plug at the cannister and the compressor engages. Put the plug back on at the cannister and the compressor comes on for a few seconds then shuts off.
Gauge on the coolant can shows middle of low when it is engaged. I'm going to run for more coolant.
Got more coolant and started the truck. Compressor does not come on. Jumped the plug again and same as above: compressor engages. Put the plug back on at the cannister and the compressor comes on for a few seconds then shuts off. So is the switch at the cannister bad? Or is the compressor shutting off because it's low on coolant and not sensing resistance?
Put 1.5 cans of coolant in while jumping the switch to the compressor. Filled it to 45 psi which the gauge says is max full, beyond it goes to Alert. Compressor now stays on and I'm getting cool air into the cabin. Not frigid, but cool. Ambient temp is 80 F.
Jumped the plug at the cannister and the compressor engages. Put the plug back on at the cannister and the compressor comes on for a few seconds then shuts off.
Gauge on the coolant can shows middle of low when it is engaged. I'm going to run for more coolant.
Got more coolant and started the truck. Compressor does not come on. Jumped the plug again and same as above: compressor engages. Put the plug back on at the cannister and the compressor comes on for a few seconds then shuts off. So is the switch at the cannister bad? Or is the compressor shutting off because it's low on coolant and not sensing resistance?
Put 1.5 cans of coolant in while jumping the switch to the compressor. Filled it to 45 psi which the gauge says is max full, beyond it goes to Alert. Compressor now stays on and I'm getting cool air into the cabin. Not frigid, but cool. Ambient temp is 80 F.
Last edited:
Acesneights1
New Member
It takes forever to charge it when that low with cycle switch coneected. I usually jump the swtich while charging. I can't beleive you got any to go in. 1.5 cans should be enough to kepp it cycling fairly consistently. If you overcharged it it will not cool good. If you don't have a recharging station that can evac and remeasure the charge(preffered method) then slowly adding refreigerant with a thermometer in the dash is about the only other way I know to do it. I wouldn't trust the half assed guage on a charging can adaptor. I would get real guages on it and see what is happening. 1.5 cans is only 1 lb of charge. People often get confused thinking those little cans are a 1lb. They are not they are 12oz. Best bet would be to put a good accurate therm in the dash and slowly add a little at a time Remember it takes time for it to change in the vehichle. IE; If you add a little it could take 15+mins to see a change in temp. Best way is a full evac and recharge. You probably have a leak. Common places on these are the seals at the compressor, the gaskets where the hoses meet the compressor and the high side charging/test port. In fact I generally don't f with that port unless there is a problem beyond a simple top off cause the minute you disturb it, it generally leaks and is a PIA to change. Requies a special socket and hope it comes out nicely. Not like the old days where you could hotswap a schrader valve. it will require draining the system to change. There will generally be wet and dust collected where the leak is. The High side port can be tested with the old "Spit" method.
I assume you have check for fan clutch operation and clean condenser/oil cooler area?
45 PSI on low side would be around 50 degrees refrigerant temp. Not an accurate way to say how your system is doing or state of charge.
Dye may help you find a leak. Shops have 134a sniffers that can track the leak quickly.
If you take the engine to 1500 RPM the clutch should cycle some but stay on for most of the time with blower on high. This only tells you if you are still low. Your outlet temp should go down at this RPM. Edit: Take it easy and do not hold it there for more than 10-15 sec and give the fan clutch time to lock in or use several big fans pointed at the front of the truck - big fans are not 20" box fans...
The proper tools include a refrigerant recovery system, gauges, vac pump, scale, and sniffer. You can cut them out by using a shop to pull a vacuum and charge it by weight yourself. Only if the 12oz cans add up to the proper weight. If not you need a scale. postal scale will do. Partial can is a pain to get right.
45 PSI on low side would be around 50 degrees refrigerant temp. Not an accurate way to say how your system is doing or state of charge.
Dye may help you find a leak. Shops have 134a sniffers that can track the leak quickly.
If you take the engine to 1500 RPM the clutch should cycle some but stay on for most of the time with blower on high. This only tells you if you are still low. Your outlet temp should go down at this RPM. Edit: Take it easy and do not hold it there for more than 10-15 sec and give the fan clutch time to lock in or use several big fans pointed at the front of the truck - big fans are not 20" box fans...
The proper tools include a refrigerant recovery system, gauges, vac pump, scale, and sniffer. You can cut them out by using a shop to pull a vacuum and charge it by weight yourself. Only if the 12oz cans add up to the proper weight. If not you need a scale. postal scale will do. Partial can is a pain to get right.
Acesneights1
New Member
Haha. That is exactly what I use. A postal scale. It works good. I personally do not like using dye. Only as a last resort but my bias comes from the older days when the stuff was a red food coloring syrupy crap that caused alot of problems. Still even the new stuff can cause damage if too much is used. I watched an idiot blow the front seal right out of the compressor. Whole underneath of the hood looked like neon.
Big T
Well-Known Member
The coolant I was using is dyed fuschia or neon green to show leaks. I measured 45 psi when I let off the trigger with the compressor on. The compressor now stays on continuously with the AC on. Interestingly, the rear overhead AC was blowing much colder than the dash. The dash felt like it was about 50. The upper rear felt real cold. I'll check it again and add some more if warranted.
Did the compressor run at all before you started?
No? Than you could have a really low charge that will starve the compressor for oil.
If you add more and the low side pressure goes up to 46 PSI from 45PSI you are entering an overcharged state. Possible restricted orface tube as well.
This is why the charge by weight is so important.
No? Than you could have a really low charge that will starve the compressor for oil.
If you add more and the low side pressure goes up to 46 PSI from 45PSI you are entering an overcharged state. Possible restricted orface tube as well.
This is why the charge by weight is so important.
Big T
Well-Known Member
Compressor did not run at all when I first started. It finally ran when I jumped it. Now that I've added coolant, it runs full time. It blows much cooler out of the rear overhead than it does out of the dash, but the dash was in the sun.
Can't do anything now as I'm on business travel in Chicago all week.
Can't do anything now as I'm on business travel in Chicago all week.
You have to pull a vacuum on the system before charging it if its been sitting any length of time. Air is a non condensable, your compressor cant make it change phase into a liquid, so the AC will never get as cold as if you got all the air out.
The smaller the system, the more sensitive it is to the state of charge. You really want your suction side at 30 to 40 PSI, that should get you 35-45 degree air at the evaporator. Dont go lower than 35psi or you will just ice up.
You should also be keeping an eye on the high side of the system. with the low side at 40PSI, and it being 90F out, High side should show around 180 PSI. If it shows more, you need to get the water and or air out of the system.
Prolly way more than you wanted to know, but I do this for a living ):h
The smaller the system, the more sensitive it is to the state of charge. You really want your suction side at 30 to 40 PSI, that should get you 35-45 degree air at the evaporator. Dont go lower than 35psi or you will just ice up.
You should also be keeping an eye on the high side of the system. with the low side at 40PSI, and it being 90F out, High side should show around 180 PSI. If it shows more, you need to get the water and or air out of the system.
Prolly way more than you wanted to know, but I do this for a living ):h
Big T
Well-Known Member
OK how do I pull a vacuum on the system?
China Tool and Freight
This will work if your not going to be doing it every day.
Did you check to see if there was anything in the system prior to topping it off?
So long as there is always net positive pressure in the system, you should be fine to just top it off. I always had trouble with the long ass lines to the rear seeping refrigerant out through the rubber hoses.
This will work if your not going to be doing it every day.
Did you check to see if there was anything in the system prior to topping it off?
So long as there is always net positive pressure in the system, you should be fine to just top it off. I always had trouble with the long ass lines to the rear seeping refrigerant out through the rubber hoses.
Big T
Well-Known Member
Thanks.
No I did check to see if there was anything in the system. I think it was completely empty as the compressor would not cycle on.
Turbine Doc
Just Another Diesel Guy
You'll want gauges now as it sounds like you are close and you don't want to overcharge it and put too much head pressure on it and kill the compressor early.