December 4, 2018

Scott Asbjornson
Chief Financial Officer
AAON INC
2425 South Yukon
Tulsa, Oklahoma 74107

       Re: AAON INC
           Form 10-K for the Fiscal Year Ended December 31, 2017
           Filed February 27, 2018
           Form 10-Q for the Fiscal Quarter Ended September 30, 2018
           Filed November 1, 2018
           File No: 0-18953

Dear Mr. Asbjornson:

       We have limited our review of your filing to the financial statements
and related
disclosures and have the following comments. In some of our comments, we may
ask you to
provide us with information so we may better understand your disclosure.

       Please respond to these comments within ten business days by providing
the requested
information or advise us as soon as possible when you will respond. If you do
not believe our
comments apply to your facts and circumstances, please tell us why in your
response.

       After reviewing your response to these comments, we may have additional
comments.

Form 10-K for the Fiscal Year Ended December 31, 2017

Selling, General and Administrative Expenses, page 14

1.    You disclose that the overall increase in SG&A in 2017, as compared to
2016, was
      primarily due to increased warranty expenses and that you have been
working on
      modifications and refinements to your warranty policy. In this regard, we
note your
      warranty expense increased by approximately 211% year over year and
lowered gross
      profit by approximately 9%. Please revise to disclose the material
factors negatively
      impacting your results so that investors can better understand the
underlying issues
      driving your warranty payments and increased expense. To the extent
management
      anticipates that warranty expense will continue to have a negative impact
on your future
      results, please provide discussion of this trend to provide investors
with more insight into
      your risks and future results of operations. Please refer to Sections
501.04 (Material
 Scott Asbjornson
AAON INC
December 4, 2018
Page 2
         Changes) and .12 (Overall Approach to MD&A) of the Financial Reporting
Codification
         for further guidance.
Management's Discussion and Analysis of Financial Condition and Results of
Operations
Cash Flows from Operating Activities, page 18

2.       We note the increase in inventory and it appears that your inventory
turnover decreased
         from 6.19 for FY 2016 to 4.77 for FY 2017. You disclose that cash
flows from operating
         activities decreased primarily due to increased purchases of inventory
during the year.
         Please revise your filing to expand your disclosures regarding cash
flows used in
         operating activities to provide more insight into the underlying
drivers of the significant
         increases in inventory between the periods presented. Refer to Section
501.13.b.1 of the
         Financial Reporting Codification for guidance.
Form 10-Q for the Fiscal Quarter Ended September 30, 2018

Note 9. Warranties, page 11

3.       As it relates to your standard warranty with terms from 18 months to
25 years, which you
         disclose obligates the company to replace parts or services your
products, tell us how you
         considered the factors in ASC 606-10-55-33 in determining your
warranties do not also
         include a service component and these warranties should be accounted
for as a separate
         performance obligation in accordance with ASC 606-10-55-34. Include in
your response
         a comparison of the warranty periods to the average life spans of each
product type.


       In closing, we remind you that the company and its management are
responsible for the
accuracy and adequacy of their disclosures, notwithstanding any review,
comments, action or
absence of action by the staff.

       You may contact Tracey McKoy, Staff Accountant, at (202)551-3772 or, in
her absence
Melissa Rocha, Senior Assistance Chief Accountant, at (202) 551-3854 with any
questions.



                                                               Sincerely,
FirstName LastNameScott Asbjornson
                                                               Division of
Corporation Finance
Comapany NameAAON INC
                                                               Office of
Manufacturing and
December 4, 2018 Page 2                                        Construction
FirstName LastName