* **Phone:** (210) 660-2424
                  !
## A/C, Heating, & Plumbing Services Near San Antonio, TX
                Toggle menu
  + 
# Why Does My Furnace Keep Going On and Off?
  /    /    /  Why Does My Furnace Keep Going On and Off?                !  17Dec2024     !Author 
Worried that your furnace is turning on and off too frequently? If your furnace keeps going on and off, it could mean one of two things:
1. It’s especially cold outside
2. Your furnace is short cycling
If it is an especially cold day, your furnace may just be turning on and off frequently because your home is getting colder faster. If that’s the case, there’s no need to worry—your furnace is just doing its job. However, **if your furnace frequently goes on and off and only runs for a minute or two, it’s short cycling**. Short cycling is bad news for your furnace because it wears out important components and increases your energy bills.
In this blog, we’ll explain what to do before calling a pro and what causes your furnace to short cycle. Need a  ASAP? We can help!
## Try these 2 DIY fixes before calling a pro
Before we jump into the reasons why your furnace may be short cycling, we’ll share two things you can do before you call a professional for help.
### DIY fix #1: Change your air filter (if it is dirty)
!
A dirty air filter restricts the flow of air to your furnace. This can cause your furnace to overheat and shut off, ultimately resulting in short cycling (more on that later).
**What to do:** Check your air filter. If it is dirty, replace it with a new, clean filter.
### DIY fix #2: Make sure nothing is blocking your vents
If you close or block your air vents, it can lead to low airflow issues in your furnace. Eventually low airflow can cause your furnace to overheat, which causes short cycling.
**What to do:** Check your air vents. Make sure all supply vents are open (even in rooms you don’t use), and make sure nothing is blocking or covering your return vent.
## When To Call an HVAC Technician
### Furnace problems that cause short cycling
If you’ve tried the above DIY fixes and your furnace is still short cycling, you’ll need to have a professional inspect your furnace and find the issue. Below we’ll go into detail about what could be causing your furnace to short cycle.
### #1: Overheating
Your furnace has a built-in safety switch called a high-limit switch. If your furnace is overheating for any reason, this switch will trigger your furnace to shut off to protect itself from damage.
Once the internal temperature of the furnace returns to normal levels, the furnace will turn back on. However, if you have an overheating problem, your furnace will quickly shut off again. This quick on/off cycle will repeat over and over again, an issue called short cycling.
So, what causes overheating problems?
* Dirty components
* Reduced or restricted airflow
* Malfunctioning blower motor or fan
* Aging furnace components
Besides changing a dirty filter and making sure all air vents are open, other overheating problems require an HVAC technician’s expertise to fix. They can safely and quickly find what is  and fix the problem.
### #2: Thermostat issues
Your thermostat is the brain of your furnace—it tells the furnace when to shut on and off. Just like any kind of electrical equipment, sometimes it can malfunction, causing your furnace to quickly shut on and off when it’s not supposed to.
A professional will need to check the thermostat’s wiring to make sure it is working properly and sending correct signals to your furnace.
### #3: Sizing problem
When it comes to furnaces, the biggest size isn’t always the best for your home. An oversized furnace will quickly heat your home then shut off abruptly. Once your home starts to get cold again, it’ll repeat the short cycling process.
Unfortunately, if it turns out your furnace is too big, you’ll need to get a new system that’s correctly sized. A professional can help you calculate the exact size system you need for your home by performing a load calculation.
Learn more about  have one of our HVAC technicians come out to your home at no cost for a free consultation.
Need a furnace repair from a San Antonio pro? Call Today! Our team of trained furnace repair technicians are standing by to help! We offer same-day service and are available for emergency service. Learn more about our repair process by visiting our  page.
               Search for:
### Categories
*  33
*  7
*  28
*  11
*  14
*  35
### Recent Posts
* January 22, 2025
* January 6, 2025
* January 2, 2025
```
     EXCELLENT     Based on 1753 reviews                        Kassie Aird  January 8, 2025   Trustindex verifies that the original source of the review is Google. Working with Schafer services plus was great, we called them with an issue with our HVAC and they were out to our home within a couple hours, Our technician, Dustin, Was great, super personable and helpful with all the questions that we asked and provided information that we needed to help us in a stressful situation! Great working with this company and Dustin!              Bruno Herrera  January 7, 2025   Trustindex verifies that the original source of the review is Google. Great service ! Mike did a excellent job cleaning out my inside house unit coils! He showed me before and after photos pictures of the coils. Beautiful job !!! He answer all my questions.He was very friendly and professional. Plus I got a 10% senior discount!!!              Chris Hendricks  January 7, 2025   Trustindex verifies that the original source of the review is Google. Extraordinary: the team set up a consultation the next business day, the diagnosis and repair were accomplished quickly and at a fraction of the price of a competing quote. My first choice every time!              Cheryl Sievers  November 26, 2024   Trustindex verifies that the original source of the review is Google. I like the cold, but the tech Rob ensured it's a Go if my new heater is needed.              Cathleen Crowell  November 25, 2024   Trustindex verifies that the original source of the review is Google. As usual, Dusten was friendly & professional.              daniel houghton  November 25, 2024   Trustindex verifies that the original source of the review is Google. Shafer has been handling several locations for me in plumbing and AC units.  They are always on time and do a great job.              Kaitlyn Korte  November 23, 2024   Trustindex verifies that the original source of the review is Google. I am so grateful to have found and built such a great relationship with Shafer Services. I use them for both my commercial property and personal home and their work ethic is superior. Mark Patino, manager of the Commercial department, is extremely professional, reliable and trustworthy. He makes you feel as if you are asking your trusted friend or family member on advice for whatever project you have going on relating to their services. This business is a perfect demonstration on how greatness attracts greatness starting from the owner(s) to the managers to the amazing and hardworking crews whom perform the work. Their high quality work is the cherry on top. I highly recommend them for all of your HVAC and plumbing projects.              GH S  November 23, 2024   Trustindex verifies that the original source of the review is Google. Outstanding Support. The plumber was very helpful and assisted me with all of my questions and concerns.
         !
Shafer Services Plus has been serving the communities in San Antonio, Texas since 1988.
License #TACLA26198E/M215
### Hours & Location
* Mon - Fri 7am - 9pm
* Sat - Sun 8am - 5pm
### Services
### Schedule Service
## (210) 660-2424
Address: 3800 San Pedro Ave, San Antonio, TX 78212
 Give us a call or Book Online to schedule a technician to come out today!
    Book online now
                       Copyright © 2025 . All rights reserved.
## Let Us Contact You!
"\*" indicates required fields
 Give us a call at (210) 660-2424 or fill out the form below and we will follow up via text and phone.Name\*  First Name    Last Name   Email\*  Phone Number\*Postal Code How can we help you?\*CAPTCHANameThis field is for validation purposes and should be left unchanged.
* **Phone:** 210-660-2424
# Privacy Policy
  /  Privacy Policy
## Privacy Policy for Shafer Services Plus
At Shafer Services, accessible from  one of our main priorities is the privacy of our visitors. This Privacy Policy document contains types of information that is collected and recorded by Shafer Services and how we use it.
### 1. Information We Collect
We collect several different types of information for various purposes to provide and improve our service to you. Here are the types of information we collect
**Personal Data**
While using our Service, we may ask you to provide us with certain personally identifiable information that can be used to contact or identify you. Personally identifiable information may include, but is not limited to:
* Name
* Phone number
* Email address
* Zip code
* Nominee Information
If you participate in our donation programs such as Shafer Serves or Shafer Cool Kids, we may collect information about individuals you nominate for sponsorship. This information includes names and details necessary for the nomination process.
**Cookies and Usage Data**
We use cookies and similar tracking technologies to track the activity on our Service and hold certain information. Cookies are files with a small amount of data which may include an anonymous unique identifier. You can instruct your browser to refuse all cookies or to indicate when a cookie is being sent.
### 2. How We Use Your Information
Shafer Services uses the collected data for various purposes:
* To provide and maintain our Service
* To notify you about changes to our Service
* To allow you to participate in interactive features of our Service when you choose to do so
* To provide customer support
* To gather analysis or valuable information so that we can improve our Service
* To monitor the usage of our Service
* To detect, prevent, and address technical issues
### 3. Sharing Your Information
We may share your personal information with third parties to help us use your personal information, as described above. For example, we use Google Analytics to help us understand how our customers use the Site.
### 4. Third-Party Services
Our Service may contain links to third-party web sites or services that are not owned or controlled by Shafer Services. Shafer Services has no control over, and assumes no responsibility for, the content, privacy policies, or practices of any third party web sites or services.
### 5. Security
We value your trust in providing us your Personal Information, thus we are striving to use commercially acceptable means of protecting it. But remember that no method of transmission over the internet, or method of electronic storage is 100% secure and reliable, and we cannot guarantee its absolute security.
### 6. Changes to This Privacy Policy
We may update our Privacy Policy from time to time. We will notify you of any changes by posting the new Privacy Policy on this page. Thus, you are advised to review this page periodically for any changes.
### 7. Contact Us
If you have any questions or suggestions about our Privacy Policy, do not hesitate to contact us at 210-227-8358.
     EXCELLENT     Based on 1760 reviews                        Holly Perry  January 20, 2025   Trustindex verifies that the original source of the review is Google. On time and very professional. Explained everything and answered all my questions              dennis hooker  January 18, 2025   Trustindex verifies that the original source of the review is Google. Technicians are always friendly, helpful, do a great job in communicating what is wrong and the process to fix the issue              Julio Quezada  January 17, 2025   Trustindex verifies that the original source of the review is Google. Excellent service              Pamela Sullivan  January 17, 2025   Trustindex verifies that the original source of the review is Google. Great service—took care of my plumbing problem quickly and efficiently! The technician was thorough in explaining the problem and went above and beyond to fix the stubborn valve!              Gary Garcia  January 17, 2025   Trustindex verifies that the original source of the review is Google. Diagnosed the plumbing repair. Did a great job repairing plumbing problem.              Dennis Means  January 16, 2025   Trustindex verifies that the original source of the review is Google. Outstanding service!  Everyone (from the service tech who came to our home, the dispatcher and even the owner) was courteous, friendly, listened well and did their best to fix my issue.  Excellent communicators and knowledgeable.  Would highly recommend them.              Jose Gomez  January 15, 2025   Trustindex verifies that the original source of the review is Google. Was fast, honest and very professional
## 210-660-2424
 Give us a call at 210-592-3397 or fill out the form below and we will follow up via text and phone.Name\*  First Name    Last Name   Email\*  Phone Number\*Postal Code How can we help you?\*CAPTCHAPhoneThis field is for validation purposes and should be left unchanged.