Old model coleman ac units

Question edited for clarity, FULL 'make model (what it is)'.

Ascertaining the date is in the link and done from Serial Number. Tonnage is only on AC Units, furnaces are graded by BTU (British Thermal Units), and that is also on the serial label.

How To Read a Coleman Serial Number - HVACpartstore

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Coleman furnace age can be determined from the serial number usually located on the data plate. There are 4 different styles of serial numbers to determine ...

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That should be a 30,000 Btu unit. Its been a while since I worked on them. The 78 is the series or model, the 30 is the capacity or btu's and the 901 indicates it is a Copeland compressor.

Check the condensor unit. May be dusty. Clean it. If still problem replace capacitor.

The limiting factor is the power available to run the device. Typically, roof air units are around 12,000 BTU.

Unless your rig is wired with a 50 amp service, you will not be able to run more than you have at the present with your 30 amp service. I have found that a rig with a microwave, a roof AC and a TV frequently cannot run all three at the same time. If you do have 50 amp service, you can add the second roof air. Also, if you have a 30 amp service, you can upgrade to 50 but that is an expensive proposition with the cord itself costing around $200.00. You would also have to upgrade the distribution panel and probably have a pro properly split up the load between the two 120 Volt AC buss'.

I hope this response helps you with your deliberation and thanks for your question @ FixYa.com

COLEMAN R.V. PRODUCTS
GO TO rvcomfort.com
Click on RVP (RV PRODUCTS)
Click on type of AC, if you can’t find the information you want there,
then click on contact us on the Green Bar.
You can get Service Support or Email address and Phone numbers

Your choices are another Dometic or a Coleman
I prefer the Coleman But the amount of extra cooling you will get by stepping up to a 15K unit will probability not be worth the added cost

Go to www.grainger.com and look for a "power pile generator" this is a millivolt thermocouple that may be just what you need to make your heater work again

The mfg. date is sometimes (depends of the brand and the size of the unit) on the serial number.And the 36 in the model number means exactly what you think 36000 BTU or 3 ton.

yOU CAN PURCHASE FILTER MATTING AT ANY HARDWARE store and cut to size. Its cheaper anyway.. It comes in rolls.

I remeber we took out a Coleman kero heater out of my grandmothers mobile home. Just had it repaired but she wanted a new unit. Would have to go and check to see how many BTU's it is and also to see if the book is there as well.