Air Systems Cleaning Specialist (ASCS)

This landmark certification enhances one’s professional development and is a world-wide credential recognizing a person’s knowledge and skills related to HVAC system hygiene. ASCS Certification can benefit you professionally in many ways, including:

  • Increased compensation
  • Enhanced career mobility and marketability
  • Increased recognition to employers, customers and industry peers

Today, many job specifications require that a certified ASCS be on a project. Having an ASCS certified technician on staff can benefit your company in many ways, including:

  • Meeting bid specifications
  • Attracting more customers
  • Meeting the ASCS requirement for NADCA membership

Get Certified

Frequently Asked Questions

What are the benefits of ASCS certification?

ASCS certification enhances professional development and is also a designated worldwide credential recognizing a person’s knowledge and skills relating to HVAC system hygiene.

Is the individual or the business ASCS certified?

NADCA's certification program certifies individuals, not companies. Certified individuals may use the credential in marketing their own expertise. Certification is not transferable to other individuals.

Any certified individual who changes companies must pay the administrative transfer fee and complete the Certification Transfer Form.

Who should become NADCA certified?

NADCA recommends at a minimum that an owner, principal, or key employee of a company become a certified ASCS. This individual must be a fulltime employee, be directly responsible for project management and should oversee all air duct cleaning projects. There is no limit to the number of company representatives who can become certified.

How was the ASCS certification examination developed?

As is customary with credentialing practices, NADCA worked with independent test development experts and industry professional Subject Matter Experts (SMEs) engaged in the practice of HVAC system cleaning to perform a job analysis for the ASCS certification. The job analysis ensures the credential reflects the most current practices in the industry and properly reflects the knowledge, skills and abilities required for cleaning and restoring HVAC systems.

Once I become certified, how do I renew my certification?

ASCS certification is renewable each year before June 30 for a fee. Click here for more information on ASCS Renewal.

Renew Now

If I fail to complete the renewal requirements for my certification, how do I become re-certified?

If a certified individual does not meet all requirements for maintaining their certification by the renewal deadline, the certification will be considered expired. In order to become re-certified and have an active ASCS credential, the individual must sit for the ASCS exam and achieve a passing score.

How to Prepare for the ASCS Exam

The ASCS examination tests the knowledge and skills needed to become successful in the HVAC inspection, cleaning and restoration industry. The exam covers a range of topics, including indoor air quality, safety, mechanical, field experience, and the ability to correctly apply practical knowledge.


No one single publication, training course or reference guide will give you all the information you need to prepare for the ASCS exam. It is strongly recommended that prior to taking the exam, test takers review the recommended reading materials listed in the ASCS Candidate's Guide that were used as references during the development of the ASCS certification exam.

Step 1: Review the ASCS Candidate's Guide

The first step in preparing for the ASCS Exam is to review the ASCS Candidate's Guide in its entirety, including the exam content outline and recommended reading list included in the Guide.

Download ASCS Candidate's Guide

Step 2: Study

There are a variety of optional recommended study materials and training opportunities available to help you prepare for the ASCS exam, including the following:

Online Training 

  • Ventilation Maintenance Technician (VMT) Course
  • ASCS to the ACR Standard Online Training Course

Classroom Training

  • ASCS to the ACR Standard Training Course
    ​(Offered at Fall Technical Conference and Annual Meeting & Exposition)


ASCS certification study materials are available for those who wish to study reference materials on their own. DO NOT order these materials if you have already registered for the ASCS Online Course or the ASCS to the ACR Standard Course, as these materials are provided upon registration for those courses. 

Sample Practice Test Questions

NADCA has developed a short list of practice test questions to give candidates a general idea of the common format of typical questions included in the ASCS Certification exam. Please note that questions are not actual test questions used in the ASCS exam. No representations or warranties are made by NADCA that completing these practice test questions will assure candidates of passing the ASCS certification exam. Candidates are encouraged to review the ASCS Candidates Guide and take the time to review recommended reference materials prior to taking the ASCS exam.

Step 3: Register to Take the ASCS Certification Exam

The ASCS exam is available at testing centers throughout the world and at the NADCA Annual Meeting and Fall Technical Conference. Candidates taking the ASCS exam at a testing center must follow these steps.

Please note: ASCS certification is renewable each year by June 30. It is your responsibility as an ASCS to maintain certification and apply for certification renewal in advance of the deadline. Certification is valid until the expiration date listed on your certificate. Any individual who passes the ASCS certification exam within the period of July 1 – February 28 will be provided with a certificate expiration date of June 30 within the year of the upcoming renewal period. Any individual who passes the ASCS certification exam within the period of March 1 – June 30, will be provided with a certificate expiration date of June 30 of the following renewal year.  

If the Member Promo Package application has been submitted, you must still create an account in the test-taker’s name, and the ASCS exam must be scheduled by a member of the NADCA staff. Contact NADCA to schedule the exam when the account has been created.

  • Visit the NADCA Testing Site.
  • In the top right-hand corner of the page, click “Create a New Account.”
  • Fill out the company information. This section requires a “Member Security Code,” which is provided upon submission of the NADCA member application. If you have lost/misplaced the “Member Security Code,” please call NADCA at 855-GO NADCA (466-2322).
  • The blue bar across the middle of the NADCA Testing Site includes an option to “Register for a Test.” Click this link to see all NADCA testing options. Choose the ASCS Exam by clicking the orange “Buy Now” box ($385). This will open a page with testing center search options.
  • For candidates with a non-member company, the ASCS exam must be scheduled in the non-member area of the NADCA Testing Site. This link is at the bottom of the testing site homepage.
  • Unless the Member Promo Package application has been submitted, payment must be made through the testing site with a valid Visa, MasterCard or American Express.
  • If a candidate fails the exam, they may schedule to retake the exam at a retake fee of $100.

Register for the ASCS Exam