03’ International 9900i A/C not cooling well

[tree98]

(07-07-2022 )Redland1 Wrote:  Since I recharged the system the fan has been running continuously.Any ideas as to why and is it bad if it runs like that?

Could be the pressure switch is bad and always telling the ECM that the a/c pressure is high which turns the fan on. Or since it started right after you charged it i would say you might have over charged it. What do the manifold gauges say the pressures are? It's costing you fuel mileage driving around with the fan on all the time and could cause component damage if it's overcharged and you keep running it. Is it blowing cold air ?

[DVT873]

How high is the head pressure? These have a high pressure switch that will turn the engine fan on. Is the AC compressor cycling correctly? post VIN. With it I can find some detaled info. Is it a Cummins? Vaguely remember some problems like this but might have been a bit older. Per a pretty good Cummins guy the ECMs would "drop" the fan cluch programming. High pressure AC switch would send the signal to the ECM that in turn ran the fan. He's long dead and that was close to 20 years back. And I don't see a lot of of 9900i's. ...One thing to try. Find the fan solenoid. It should have 2 wires. If it is bolted to something metal unbolt it and secure it to something non metallic like a harness bundle. Peolpe don't beleive this but I have personally seen this be a problem several times over the years. Easy and cheap to try. The mounting loop around the solenoid is supposed to be insulated from the body but not always.

[Redland1]

Update:Changed the high pressure switch out and still was cycling more than other trucks parked next to me at truck stops and also more than my buddies trucks.Switched out that switch two days ago and this morning the A/C stopped blowing cold air.Started looking around to see what I found and saw that the compressor wasn’t engaging.Checked all A/C related fuses and they were good and then swapped A/C relays with similar relays and still the compressor wouldn’t engage.Decided I was going to try running power directly to it like Rawze does to add refrigerant and see if it engaged.When I looked at the compressor wires they are both black and no way of telling which is negative or positive.So I called the place that sold it to me and they said it doesn’t matter because it doesn’t have a capacitor.Put power to it and saw a little puff of smoke and I then knew it did matter.

I don’t have many choices as far as mechanics and parts stores so I called around to the only two reputable shops around and they are booked a week out.Called the only heavy truck parts store in town and they had the compressor.Installed it and filled it up with refrigerant but when I turned the A/C on the compressor would still not engage.Noticed that the wires on the new compressor were red and black so I ran power directly to it and sure enough it turned on and I then ran enough cable into the cab to install a switch.How long should I run it continuously before shitting it off?
BTW Im in North Dakota doing oilfield work so this is just temporary until I get back home to Texas.
Also what could have caused the compressors not to run?

[Rawze]

(07-15-2022 )Redland1 Wrote:  ....How long should I run it continuously before shitting it off?
...

If you bypass the compressor and force it on, it will not have any proper pressure regulation, and it will destroy the A/C system /... or blow the guts out of something if the pressure gets too high!!!. The clutch cannot be simply "jumpered on". to make the A/C work.

When I bypassed mine in the video... IT WAS TO GET ONLY THE FIRST CAN OF REFRIGERANT IN IT ONLY -- BECAUSE IT WAS BONE DRY!!!. and then to plug it back in to the system so that the cab controller, etc. can properly run it after that.

I mention this at 2:20 in the video...
https://youtu.be/5aDnVazYftA

[Rawze]

(07-15-2022 )Redland1 Wrote:  ...

Started looking around to see what I found and saw that the compressor wasn’t engaging.
...

assuming for a moment that it is similar to a Prostar ... unsure about that, but for a Prostar ...

someone can keep guessing at it and fighting it because they don't understand WHY it refuses to come on. -- WATCH MY VIDEOS!...

(assuming all the wiring/compressor, etc. is ok, and no fuses are blown) ...
Then there are only ever 2 reason it will not come on at all!!!. The high pressure sensor, or one of the 2 thermistors acting up>...

a). It can be that the high pressure switch is reporting less THAN 50-PSI PRESSURE ... I.E.> it thinks there is no refrigerant at all. --=(or more than 350-psi pressure if it is running and kicks out)==-. A bad wire or plug, or bad HP sensor can cause it to think there is no pressure.

AND/OR

b). One (or both) of the 2 thermistors at the expansion valve IS NOT READING CORRECTLY AND IS OUT OF RANGE!. -<<< THIS IS THE MOST COMMON PROBLEM ON ALL A/C SYSTEMS ON Internationals!!.. and it is a plague!.. sometimes even with brand new sensors.

it is simple as that!.

OTHERWISE.. if it is simply unhappy.. it will actualy kick on and run for exactly 10 minutes.. and get cold (or at least try to) .. then fault out -- if the thermistors are still reading incorrectly, but no enough to have it not come on at all.

===========

SO.. in your case.. if the high pressure switch is reporting at least 50 PSI.. THEN YOUR ISSUES ARE MOST LIKELY BAD THERMISTORS!.. AND YES, I HAVE SEEN PEOPLE BUY BRAND NEW ONES AND THEM NOT BE UP TO SPEC.. RIGHT OUT OF THE BOX!... ESPECIALLY AFTERMARKET THERMISTORS THAT DO NOT HAVE THE INTERNATIONAL LOGO ON THE BOX.

GO GET A BRAND NEW OEM THERMISTOR ... TAKE AN OHM METER AND MEASURE ITS RESISTANCE RIGHT OUT OF THE BOX!... AND THEN GO MEASURE THE RESISTANCE OF THE 2 THAT ARE ON THE A/C SYSTEM (EVERYTHING AT OUTSIDE TEMPS, NOT RUNNING.) .. THEY SHOULD BOTH READ REALLY CLOSE TO THE SAME VALUE AS THE ONE IN THE BOX !!!!. -- THAT IS HOW YOU CHECK THEM!.

What most people find is that the new one usualy reads about 7,000 - maybe 9,000 ohms, depends on temps outside.. and one of them (or both sometimes) on the truck are reading only maybe 300 ohms or something significantly lower .. this means that it is bad!.

ALSO.. water or moisture in the wiring or plugs causes this same problem... as it shorts out the readings and causes them to read low at the cab controller.

[DVT873]

Redland1. Post the VIN aka serial # of the truck. You will get nowhere w/o correct service information. The 9900i is purely analog unless it has APADS. It DOES NOT have thermistors or a body computer. Switches, fuses and relays is all. The VIN will tell me if it was built with APADS or not.

[Redland1]

(07-16-2022 )DVT873 Wrote:  Redland1. Post the VIN aka serial # of the truck. You will get nowhere w/o correct service information. The 9900i is purely analog unless it has APADS. It DOES NOT have thermistors or a body computer. Switches, fuses and relays is all. The VIN will tell me if it was built with APADS or not.

2HSCHAPRX3C060887

[DVT873]

Not built with APADS. Check your Rawze email. Sent you a dropbox link with 3 docs. The circuit diagrams for your truck, the A/C manual specific to your truck and a general info and theory of A/C for your general system. Link dies in 72 hours. Good luck Mr. Phelps.

[Redland1]

(07-16-2022 )DVT873 Wrote:  Not built with APADS. Check your Rawze email. Sent you a dropbox link with 3 docs. The circuit diagrams for your truck, the A/C manual specific to your truck and a general info and theory of A/C for your general system. Link dies in 72 hours. Good luck Mr. Phelps.

Thank you!