TST and No A/C on 03

[Reb.B]

Third truck to do this. All have been California 03 235 hp trucks. Turn on TST box with gauges past level 2 and it turns off the A/C clutch. When I turn the box down to 0 and the a/c clicks back on. This is What i tried: moved the ground wire from battery, body, body, and now engine, moved the full time 12v power and the key 12v power, I pulled the thermocoupler out of the wirering harness and pulled it out, and I pulled the ground wire away from the TST loom. My first customer said he had somebody move the ground wire and its fine. I called TST and they were no help, said they never heard of that before, Piers' guys said move the ground to the body, and J. Donnelly said something about the 5. 8 volt power supply to a/c gets a bad signal from TST. Anybody who has expierienced this and fixed it, please let me know, Thanks, Richard

 

[PHeadings]

I have the same problem with my 2004. 5. If I get on the gas it will turn off the a/c compresser. It will come back on when I push the a/c button twice.

 

[ThomasLawrence]

Ditto here. I ran an early TST box for a little over a year, with no problems. I recently switched to a twin-turbo program, and now (sometimes) the A/C will start blowing warm and humid. If I shut the A/C off, then back on, it comes back, and usually stays running. I haven't started playing with the ground, or anything else, because it's just not much of a nuisance (yet).



-Tom

 

[Matt400]

I have been looking at trying a TST but would also want my A/C



In looking at the connections they have you do I question taping into fuse #28 with the Orange wire from the timing harness as that circuit is tied to the A/C compressor clutch relay. The TST may be interfering with that relay.



I think you should call TST back and ask why they want that circuit taped? Also it would be a good idea to find out what the Orange wire is for and how much current it draws.



Post back what you find cuz I still may want one.

 

[Reb.B]

well thats what i thought. I moved them to higher fuse rated spots. 10 amp vs. 20 amp. I moved the orange and the red, still the same problem.

 

[Matt400]

Another thought is that since the TST controls the "high voltage" circuit of the injectors would be to move it off of the top of the fuse box away from relays in that box.

Also to make sure the injector harness doesn't run close to any A/C circuits.

 

[Reb.B]

Thats idea. I'll try that. The box is on top of the fuse box. When i was moving the ground i'm pretty sure i had it pulled off and away from the fuse box. I pulled the map sensor part of the box off too and it still does it. Here's whats funny, all of my testing is done at an idle with the truck in park. I can turn the torque up to 9 no problem, and i can turn the box on level 1 no problem, but as soon as i click it up to 2 or higher the clutch disengages. I turn it to 0 and it engages. When its on 2 or above, it will turn off, then a little later it will cycle like it has no freon. It will just click on and then off. turn the box down to 0 and everthing is normal. Now here's the question, does the box fuel anymore at an idle when the box is turned up? My next test will be to connect the switched 12v, the constant 12v, and the ground to a seperate battery and see what happens. This will hopefully eliminate those three from being the problem.

 

[Reb.B]

Well i'm even more confused now. First i'm really upset with TST by building a box that kills the engine when the box is disconnected. Now that thats out of the way, here's what I found. I moved the box off the fuse box, no change. I disconnected the switched and constant 12v along with the negative wire. At level 0 and 1 the engine ran fine and the a/c stayed on, when i upped it above 1, (2-9) the engine would run bad and want to die. It died a couple of times. I thought maybe the ground wasn't big enough so i cut the wire more than half to shorten it and reduce the resistance. No change, it would turn off the a/c. The only time it did not turn off the a/c was when both the 12v and negative to the box was attached to another battery, but the engine ran rough. I don't know, getting ready to through my hands up in the air.

 

[JRuggenberg]

I Have a 03 3500 ctd with a TST and mine would throw cam, crankshaft and map codes along with the AC not working. After I moved the ground to the inside firewall I have'nt thrown a code and the AC works fine. Oo. I have'nt ran mine at the higher power settings but it works fine at 3 and 2 te.

Hope this helps.

 

[Matt400]

The only time it did not turn off the a/c was when both the 12v and negative to the box was attached to another battery, but the engine ran rough.

I could see a separate battery not connected to the vehicle and just the TST producing this symptom. The fact it did not turn off the A/C set up that way may mean nothing because it wasn't able to function correctly with an isolated power source.



Its interesting how some have had the trouble and it went away with moving the ground. Don't give up yet. . how about instead of moving the ground- maybe add extras?

You could make sure it is grounded to the battery, engine and body.



I will look more closely at the A/C circuit to see what else I can come up with.

 

[GearyT]

Have any of the California trucks been reflashed. My California truck's A/C would blow cold during driving and idling afterwards but, when first started it would short cycle the A/C compressor until the coolant temperature was up to operating temp. After the reflash (I think there was a TSB for it) the A/C blows cold all the time even with the TST on 5/5.

 

[Reb.B]

hmmm, the re-flash might be the trick. I've moved the ground all over, but i'll go crazy with it and add grounds. Anybody know what the tsb or the reflash is called? My truck does the same thing on the morning a/c not working well. Oh one more thing, is it only CA trucks, or is this a problem all over?

 

[Matt400]

I would be curious to know from BOTH those not having the trouble and those that do,

to know if you did -or- did not have this TSB performed.



Only because software changes were made relating to the A/C and camshaft position sensor. Maybe we can establish a pattern related to this flash and the TST??



I know I had this flash done for no compressor engagement at idle in hot weather but have yet to try out a TST.

 

[dan shss]

hmmm, the re-flash might be the trick. I've moved the ground all over, but i'll go crazy with it and add grounds. Anybody know what the tsb or the reflash is called? My truck does the same thing on the morning a/c not working well. Oh one more thing, is it only CA trucks, or is this a problem all over?

I have the 305 engine and mine cycles at idle,,Time for a reflash,Our ground wire relocation.

 

[BHaner]

I had the same problem with the A/C kicking off... Moved the TST ground into the framework under the dash. Problem fixed.

 

[dan shss]

I put my tst on 1/1 last night and the a/c would stay on,,I need to try and move the ground wire today... Any setting over 2 the clutch would start cycling

 

[Reb.B]

well i moved the ground inside the cab on a seperate screw it it has worked fine for two days. Now that we know what to do, i sure would like to know why this fixes it. OH, by the way, i looked in the archive the other day about mistery switches, and had no luck. I wired it like i do the older rigs, and it worked perfect, only problem i had was finding the right spot to put the switched 12v supply for the trans relay.

 

[PHeadings]

See, hard work does pay off, glad to see you fixed it. I will have to move my ground this weekend.

 

[strokerschmoker]

I WAS seeing the same problems with the A/C cycling in and out. Today was the first day it didnt kick out and Im betting it was because of me moving the ground wire into the dash framework. Looks like you guys saved me again. Thanks a million

 

[Tomeygun]

I WAS seeing the same problems with the A/C cycling in and out. Today was the first day it didnt kick out and Im betting it was because of me moving the ground wire into the dash framework. Looks like you guys saved me again. Thanks a million

Funny, I have been trying different ground methods with no fix other than the one we all know about the one under the dash - Something about my brain hates when we fix something without knowing why the fix works...



Ahh heck, at least it worked!



PS - I tryed the ground by the driver hood strut, and it works but only when the TST is on like 5/2 or lower - maybe because it is not adding any hp most of the time on that low of a setting... anyway, back to sleep