Location of relay, A/C low and high pressure sensor for cat 303c

Need help finding locations of A/C compressor relay, low and high pressure sensor or does one sensor control both low and high pressures and evap thermistor location.

We need your help to supply a machine Serial Number in order to answer your question.

Model # 303.5C serial # CAT30335CCDMY03166

Please let me know thank

Thanks for the information. Check your messages for some info I think should answer all your questions. If not please ask any other questions back here.

hey Nige since we're on this topic.. FPK02319 304C CR just for giggles I got out my parts book.. I have as best I can tell a factory installed AC system but when I go into the parts book the only depictions I can find are the hoses and the dryer... can't find parts like condenser, compressor, evaporator, expansion valve... nada.. does cat have an addendum or something specific for the AC components

So you don't have the illustrations below.? (these are just a couple of examples) Is your parts manual OEM or "other".? If it is OEM what is the Cat Publication reference.?

thx Nige it is a cat book SEBP4462-15 using a couple part numbers I'd found elsewhere I looked them up in the numerical index in the back of the book and found the above pictures in my book as well... then I discovered the small section that shows the numbers I was interested in are not depicted specifically other than in the big HVAC box.. I think it says "not illustrated" at least I've got the part numbers for the pieces I need so that's a start.. taking the box apart is always fun but I've already done it a couple times.. my AC compressor crapped the bed so I plan on replacing it along with the condenser, dryer, expansion valve and evaporator.. then I only need to flush the lines.. seems to be different schools of thought on how effective flushing the condenser and evaporator are.. they're not stupid expensive so I'll just do that..

jbernielh said: it is a cat book SEBP4462-15 Click to expand... The latest iteration is SEBP4462-30, but even so your book should have at least the basics in it. All the AC system components should appear in the "Operator Station" section. The high-level Group Number appears to be 282-9305 Air Conditioner Arrgt. Apart from that, the AC compressor, lines, and condenser appear in separate groups.

jbernielh said: thx Nige it is a cat book SEBP4462-15 using a couple part numbers I'd found elsewhere I looked them up in the numerical index in the back of the book and found the above pictures in my book as well... then I discovered the small section that shows the numbers I was interested in are not depicted specifically other than in the big HVAC box.. I think it says "not illustrated" at least I've got the part numbers for the pieces I need so that's a start.. taking the box apart is always fun but I've already done it a couple times.. my AC compressor crapped the bed so I plan on replacing it along with the condenser, dryer, expansion valve and evaporator.. then I only need to flush the lines.. seems to be different schools of thought on how effective flushing the condenser and evaporator are.. they're not stupid expensive so I'll just do that.. Click to expand... You got it, cleaning the coils is a judgement call, based on the mode of failure and examination. If the compressor ate itself and shared that love everywhere, yeah, you may not be able to clean the coils. Prob a quick check is I think those little systems are fixed orifice, not TXV, so if you pull that, it will have a 'last chance' filter screen. If it's clean and intact, there is a good chance you are good on the evap. Condenser always needs a hard. If no TXV, you would not have a receiver, which is a receiver/dryer, and would catch any debris. But don't underestimate the lines! That rubber can hold particles. I prefer to shoot pigs through the lines and catch them so you can evaluate.

I've watched pigs getting shot through big pipelines... hard to imagine on the AC lines... where do you find such little pigs? when it comes to system orings are the cheap ones on amazon adequate or does one need to visit the auto parts store? it does have a receiver/dryer in the system mounted right by the condenser coil.. I was wondering if there might be filters in the system anywhere.. and how much crapola the dryer would catch from the compressor.. thx much for the input

Pigging AC lines is a daily practice. You can find/use many things from maybe no lint rag pieces, on up to pro pigs. Yep, can buy them in kits. Shoot em with N usually but comp air is probably fine if clean for these small systems. It's a total crapshoot on quality Orings!!! What you WANT is PTFE (teflon), but I am seeing many that are dyed but really just Buna-N POS! Honestly quality Buna will work, but China junk will crack quickly, they plan it that way to ruin America. Auto parts stores are wildly variable. Somewhere like NAPA will have you covered, Oreilly, I just don't know. If they don't tell you what they are, F em! You want PTFE and they like to just say "AC Orings". GM made that mistake decades ago on valve stem seals. If you have a receiver, NOT a accumulator, then you likely have a TXV, and the receiver will have the filter. It is a nice big filter. That layout is compressor - condenser - receiver - TXV. This is why looking at the condenser will tell you things. But the receiver should have caught 100% of the debris. I guess confirm what system you have.

cat part number is 176-1902 and they call it a receiver assembly so who knows

I'll go to finning to get the o-rings... should be a safe bet

jbernielh said: cat part number is 176-1902 and they call it a receiver assembly so who knows Click to expand... Yeah, that appears to be a receiver. Easy to tell in the machine. Line from condenser goes right to it. An accumulator will be on suction side, after evap. Usually more like a pop can because it doesn't have near the pressure.

Foam earplugs work great for smaller lines.

Okay Nige here’s one for you Does cat have a build sheet for each machine on file? If so is it possible to research the part numbers of the various components installed at manufacture.. just curious as to what it would show in comparison to what the parts book says should be there.. Just thinking of my condenser, evaporator and expansion valve.. Could save a lot of hassle with return shipping and screwing around if you order what isn’t actually installed

jbernielh said: Does cat have a build sheet for each machine on file? Click to expand... Only at a high level, usually shows what options were fitted to a base machine. It likely would not show the level of detail you are asking about. In the case of AC there will only be one option. Either a machine has it or it doesn’t.

jbernielh said: If so is it possible to research the part numbers of the various components installed at manufacture. Click to expand... See the attached. The AC is part of the Cab Arrgt. Unless each line of Page 1 was expanded then it is highly unlikely the information would be useful for parts ordering purposes.

thx Nige.. always interesting stuff to look at.. just for giggles I started looking for a part number for the pressure switch (high/low) in the AC system.. it's located at the HVAC box in the cab, just off floor level by the expansion valve.. it's not mentioned in the "not depicted" section of the box and I finally found it shown in the AC line pages but no indication of a part number.. I did a google search for various expansion valves in other cat mini's and looked through the numerical section of the parts book to no avail..